CN111245336A - Servo drive circuit - Google Patents
Servo drive circuit Download PDFInfo
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- CN111245336A CN111245336A CN202010123076.9A CN202010123076A CN111245336A CN 111245336 A CN111245336 A CN 111245336A CN 202010123076 A CN202010123076 A CN 202010123076A CN 111245336 A CN111245336 A CN 111245336A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
Abstract
The application discloses servo drive circuit relates to servo drive technical field, and this servo drive circuit includes control circuit, charging circuit, bus capacitance, discharge circuit, electric capacity detection circuitry and power drive circuit, and wherein, control circuit is connected with charging circuit, discharge circuit, electric capacity detection circuitry and power drive circuit respectively, and charging circuit is connected with bus capacitance, and bus capacitance is connected with discharging circuit, electric capacity detection circuitry and power drive circuit respectively. The charging circuit charges for the bus capacitor, the discharging circuit discharges the bus capacitor, the capacitance detection circuit collects voltage data of the bus capacitor in the discharging process, the control circuit calculates an actual capacitance value of the bus capacitor according to the collected voltage data, and determines an aging state of the bus capacitor according to the actual capacitance value of the bus capacitor, so that fault early warning can be performed before the bus capacitor is abnormal, and comprehensive monitoring of the bus capacitor is achieved.
Description
Technical Field
The application relates to the technical field of servo drive, in particular to a servo drive circuit.
Background
The servo drive circuit is a common drive system in the field of automatic production, and absorbs high pulse current at a bus end of the servo drive circuit through a bus capacitor so as to ensure the safety of the servo drive circuit. In the operation process of the servo drive circuit, because the load of the servo motor changes greatly and acceleration and deceleration are very frequent, the impact on the bus capacitor is strong, and the bus capacitor is easy to break down, so that the bus capacitor needs to be monitored for faults.
In the prior art, a method for monitoring a fault of a bus capacitor in a servo drive circuit is as follows: and detecting the voltage of the bus capacitor, and judging that the bus capacitor has a fault when the voltage of the bus capacitor is over-voltage or under-voltage.
However, the above monitoring method can only obtain two results, that is, a result that the bus capacitor has a fault or has no fault, and the monitoring of the bus capacitor is not comprehensive.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a servo drive circuit capable of monitoring a bus capacitance comprehensively, in order to solve the problem that the bus capacitance cannot be monitored comprehensively.
The embodiment of the application provides a servo drive circuit, including control circuit, charging circuit, bus capacitance, discharge circuit, electric capacity detection circuitry and power drive circuit, wherein:
the control circuit is respectively connected with the charging circuit, the discharging circuit, the capacitance detection circuit and the power driving circuit, the charging circuit is connected with the bus capacitor, and the bus capacitor is respectively connected with the discharging circuit, the capacitance detection circuit and the power driving circuit;
the charging circuit is used for charging the bus capacitor under the control of the control circuit, after the bus capacitor is fully charged, the discharging circuit is used for discharging the bus capacitor under the control of the control circuit, the capacitance detection circuit is used for collecting voltage data of the bus capacitor in the discharging process under the control of the control circuit and sending the collected voltage data to the control circuit, the power driving circuit is used for being communicated with the bus capacitor and driving a motor under the control of the control circuit, the control circuit is used for calculating the actual capacitance value of the bus capacitor according to the voltage data collected by the capacitance detection circuit and determining the aging state of the bus capacitor according to the actual capacitance value of the bus capacitor.
In an embodiment of the present application, the servo driving circuit further includes a conductive switch, the conductive switch is connected in parallel with the charging circuit, and the charging circuit is provided with a charging resistor.
In an embodiment of the application, the control circuit is configured to first control the conductive switch to be turned off, and control the charging circuit to charge the bus capacitor, and when the bus capacitor is fully charged, the control circuit controls the charging circuit to be turned off, and controls the conductive switch to be turned on.
In one embodiment of the present application, the discharge circuit includes a first discharge circuit and a second discharge circuit, wherein:
the first discharge circuit and the second discharge circuit are respectively connected with the bus capacitor in parallel.
In one embodiment of the present application, a resistance value of the first discharge circuit is greater than a resistance value of the second discharge circuit.
In one embodiment of the present application, the first discharge circuit includes a relay and a first discharge resistor connected in series with each other, wherein:
the relay is connected with the control circuit, and the first discharge resistor is connected with the bus capacitor;
and the relay is used for switching on or off under the control of the control circuit.
In one embodiment of the present application, the second discharge circuit includes a switching transistor and a second discharge resistor connected in series with each other, wherein:
the switching triode and the second discharge resistor are respectively connected with the bus capacitor;
the switching triode is also connected with the control circuit and used for being switched on or switched off under the control of the control circuit.
In one embodiment of the present application, the control circuit is configured to control the first discharging circuit to decrease the voltage of the bus capacitor to a first target voltage, and then control the second discharging circuit to decrease the voltage of the bus capacitor from the first target voltage to a second target voltage.
In one embodiment of the application, a collector of the switching triode is connected with one end of the second discharge resistor, an emitter of the switching triode is connected with the bus capacitor, and a base set of the switching triode is connected with the control circuit; the other end of the second discharge resistor is connected with the bus capacitor.
In one embodiment of the present application, a capacitance detection circuit includes a first detection resistor, a second detection resistor, and an isolation amplifier, wherein:
the first detection resistor is connected with the second detection resistor in series, and the isolation amplifier is connected with the second detection resistor in parallel and is connected with the control circuit;
the isolation amplifier is used for collecting voltage data of the bus capacitor on the second detection resistor in the discharging process and sending the collected voltage data to the control circuit.
In one embodiment of the present application, a sum of the resistance value of the first detection resistor and the resistance value of the second detection resistor is larger than the resistance value of the discharge circuit.
The beneficial effects brought by the technical scheme provided by the embodiment of the application at least comprise:
the servo drive circuit comprises a control circuit, a charging circuit, a bus capacitor, a discharging circuit, a capacitor detection circuit and a power drive circuit, wherein the control circuit is respectively connected with the charging circuit, the discharging circuit, the capacitor detection circuit and the power drive circuit; the charging circuit is used for charging the bus capacitor under the control of the control circuit, after the bus capacitor is fully charged, the discharging circuit is used for discharging the bus capacitor under the control of the control circuit, the capacitance detection circuit is used for collecting voltage data of the bus capacitor in the discharging process under the control of the control circuit and sending the collected voltage data to the control circuit, the power driving circuit is used for being communicated with the bus capacitor and driving a motor under the control of the control circuit, the control circuit is used for calculating the actual capacitance value of the bus capacitor according to the voltage data collected by the capacitance detection circuit and determining the aging state of the bus capacitor according to the actual capacitance value of the bus capacitor. In this embodiment, through carrying out on-line monitoring to the bus capacitance among the servo drive circuit, acquire the actual capacitance value of bus capacitance in real time to confirm the ageing state of current bus capacitance according to the actual capacitance value of bus capacitance, just so can carry out the trouble early warning before bus capacitance appears unusually, thereby realize the comprehensive monitoring to bus capacitance.
Drawings
Fig. 1 is a circuit diagram of a servo driving circuit according to an embodiment of the present disclosure;
fig. 2 is a circuit schematic diagram of a charging circuit and a conductive switch provided in an embodiment of the present application;
fig. 3 is a circuit schematic diagram of a discharge circuit provided in an embodiment of the present application;
fig. 4 is a circuit schematic diagram of a capacitance detection circuit according to an embodiment of the present application.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
The servo driver is also called a servo amplifier or a servo controller, and is a device for controlling a servo motor. High precision transmission control is generally achieved through position control, speed control and torque control. The servo driver is provided with a servo driving circuit for realizing the electric control function of the servo driver.
The existing servo drive circuit generally comprises a sorting filter circuit, a bus capacitor, a power drive circuit and a control circuit. The control circuit comprises a microprocessor, and the microprocessors of the current mainstream servo drivers all adopt digital signal processors. The digital signal processor is internally integrated with a motor control special integrated circuit, has higher operation speed and stronger floating point operation function, and can realize a complex control algorithm.
In the servo driving circuit, the control circuit is generally connected to the power supply, the rectifying and filtering circuit, the bus capacitor and the power driving circuit, respectively, wherein the rectifying and filtering circuit and the power driving circuit are connected by the bus, and the bus capacitor is bridged between the buses. The rectifying and filtering circuit is used for rectifying industrial alternating current provided by a power supply and then supplying power to the bus capacitor, the bus capacitor is used for stabilizing bus voltage and supplying power to the power driving circuit, and the power driving circuit is used for inverting direct current on the bus capacitor into alternating current to drive the servo motor to operate.
In the working process of the servo drive circuit, the load change of the servo motor is large, the acceleration and the deceleration are very frequent, and in addition, the surge current of starting at each time, the reverse voltage impact during emergency braking and the frequent power on and power off can cause impact on the bus capacitor and cause certain damage to the performance of the bus capacitor. On the one hand, when the power supply harmonic wave is large, the voltage ripple on the bus capacitor is large, the temperature of the bus capacitor rises, and the service life of the bus capacitor is shortened due to high temperature. On the other hand, the electrolyte of the bus capacitor can be gradually volatilized, so that the capacitance value of the bus capacitor can be gradually reduced, and the health state of the servo driver tends to be deteriorated. Therefore, fault monitoring of the bus capacitance is required.
In the prior art, a method for monitoring a fault of a bus capacitor in a servo drive circuit is as follows: and detecting the voltage of the bus capacitor, and judging that the bus capacitor has a fault when the voltage of the bus capacitor is over-voltage or under-voltage. The monitoring method can only obtain two results of the fault or no fault of the bus capacitor. And the early warning can not be made before the bus capacitor fails, and the health state of the bus capacitor can not be evaluated. Therefore, the monitoring method cannot fully monitor the bus capacitance.
The servo drive circuit comprises a control circuit, a charging circuit, a bus capacitor, a discharging circuit, a capacitor detection circuit and a power drive circuit, wherein the control circuit is respectively connected with the charging circuit, the discharging circuit, the capacitor detection circuit and the power drive circuit; the charging circuit is used for charging the bus capacitor under the control of the control circuit, when the bus capacitor is fully charged, the control circuit controls the power driving circuit to operate, the power driving circuit stops operating after operating for a certain period of time, at the moment, the discharging circuit is used for discharging the bus capacitor under the control of the control circuit, the capacitance detection circuit is used for collecting voltage data of the bus capacitor in the discharging process under the control of the control circuit and sending the collected voltage data to the control circuit, the power driving circuit is used for being communicated with the bus capacitor and driving the motor under the control of the control circuit, the control circuit is used for calculating the actual capacitance value of the bus capacitor according to the voltage data collected by the capacitance detection circuit and determining the aging state of the bus capacitor according to the actual capacitance value of the bus capacitor. In this embodiment, through carrying out on-line monitoring to the bus capacitance among the servo drive circuit, acquire the actual capacitance value of bus capacitance in real time to confirm the ageing state of current bus capacitance according to the actual capacitance value of bus capacitance, just so can carry out the trouble early warning before bus capacitance appears unusually, thereby realize the comprehensive monitoring to bus capacitance.
As shown in fig. 1, which is a schematic structural diagram of the servo driving circuit of this embodiment, the servo driving circuit includes a control portion and a power driving portion, where the control portion includes a control circuit 101, and the power driving portion includes a charging circuit 102, a bus capacitor C, a discharging circuit 103, a capacitor detecting circuit 104, and a power driving circuit 105.
The power driving circuit 105 is connected with a power supply through a charging circuit 102 and a bus, and a bus capacitor C, a discharging circuit 103 and a capacitor detection circuit 104 are connected to the bus in a crossing manner. Meanwhile, the control circuit 101 is connected to the charging circuit 102, the discharging circuit 103, the capacitance detection circuit 104, and the power drive circuit 105 on the bus, respectively.
In this embodiment, the bus capacitor C may be an aluminum electrolytic capacitor, a metal film capacitor, or the like.
Optionally, the bus capacitor C is an independent capacitor, or a plurality of capacitors may be formed by connecting a plurality of capacitors in parallel. The equivalent capacitance obtained by connecting a plurality of capacitors in parallel can be used for carrying out online evaluation on the aging state of a bus capacitor C formed by the plurality of capacitors.
In this embodiment, the microprocessor in the control circuit 101 may send control signals to the charging circuit 102, the discharging circuit 103, the capacitance detecting circuit 104, and the power driving circuit 105, respectively, based on the control circuit 101, so as to implement corresponding functions.
In an optional implementation manner, in this embodiment, the servo driving circuit may further include a rectifying and filtering circuit. The rectifying and filtering circuit is connected with the power driving circuit 105 through a bus, and the rectifying and filtering circuit is used for rectifying industrial alternating current input by a power supply and then inputting the rectified alternating current to the bus.
When the servo driving circuit works normally, the servo driving circuit is powered on initially, and the control circuit 101 is powered on and starts to work. A microprocessor in the control circuit 101 (hereinafter, simply referred to as the control circuit 101 for convenience of description) controls the charging circuit 102 to charge the bus capacitor C. When the bus capacitor C is fully charged, the control circuit 101 controls the power driving circuit 105 to be connected with the bus capacitor C and drive the motor, and in the running process of the motor, the control circuit 101 can control the capacitor detection circuit 104 to acquire the voltage of the bus capacitor C in real time. The capacitance detection circuit 104 can send the collected voltage of the bus capacitor C to the control circuit 101, and the control circuit 101 can determine whether the bus capacitor C has an overvoltage or undervoltage fault according to the received voltage of the bus capacitor C.
It should be noted that, in this embodiment, the power supplies directly supply power to the bus and the control circuit 101, and when the bus is powered off, the control circuit 101 may still be powered on.
After the power driving circuit 105 in the servo driving circuit drives the motor to operate for a preset time, the bus capacitor C in the servo driving circuit can be monitored on line, and the specific process is as follows: the control circuit 101 may control the power driving circuit 105 to stop operating, and after the power driving circuit 105 stops operating, the control circuit 101 controls the charging circuit 102 to turn off and no longer charge the bus capacitor C. Then, the control circuit 101 controls the discharge circuit 103 to be turned on, the bus capacitor C is discharged through the discharge circuit 103, and meanwhile, the control circuit 101 controls the capacitor collection circuit to collect voltage data in the discharge process of the bus capacitor C. The capacitance detection circuit 104 may send the collected voltage data to the control circuit 101. The control circuit 101 may calculate the capacitance value of the bus capacitor C according to the voltage data collected by the capacitance detection circuit 104, so as to determine the actual capacitance value of the bus capacitor C after the servo drive circuit operates for a period of time, and the control circuit 101 may also determine the aging state of the bus capacitor C according to the actual capacitance value of the bus capacitor C.
Optionally, in this embodiment, in the discharging process of the bus capacitor C, the capacitance detection circuit 104 may acquire a plurality of voltage data of the bus capacitor C in the discharging process according to a preset sampling frequency. Accordingly, the control circuit 101 calculates the actual capacitance value of the bus capacitor C according to the plurality of voltage data during the discharging process of the bus capacitor C.
Optionally, in this embodiment, the process of calculating the actual capacitance value of the bus capacitor C by the control circuit may include the following steps:
establishing a voltage relation according to the voltage of the bus capacitor C, wherein the voltage relation is as shown in a formula (1):
wherein u isc(t) represents the voltage data of the bus capacitor C at the tth sampling time, R3The resistance value of the resistor in the discharge circuit is shown, and C shows the actual capacitance value of the bus capacitor C. The product of the resistance value and the capacitance value represents the time constant of the discharge circuit, and the dimension is 'second'.
After transforming equation (1), equation (2) can be obtained:
wherein, UdcIs a first target voltage.
Combining equation (1) and equation (2) yields equation (3):
R3C(uc(i+1)-uc(i))+Ts·uc(i) 0, i 1,2, n-1 equation (3).
Wherein n represents the number of voltage data collected, uc(i +1) represents the (i +1) th voltage data collected, uc(i) Representing the i-th voltage data, T, acquiredsRepresenting the sampling period.
After transforming equation (3), equation (4) can be obtained:
after transforming equation (4), equation (5) can be obtained:
uc(i+1)＝a·uc(i) wherein, in the step (A),
in the process of collecting voltage data, there will generally be a measurement error, and in this embodiment, the measurement error of the ith voltage data can be represented by formula (6):
δi＝uc(i+1)-a·uc(i) equation (6).
The sum of the variances obtained from equation (6) can be given as shown in equation (7):
substituting equation (6) into equation (7) yields equation (8):
x2＝∑(uc(i-1)-a·uc(i))2equation (8).
By taking the partial derivative of a in equation (8) and making it equal to zero, equation (9) can be obtained:
∑(uc(i+1)-a·uc(i))·uc(i) equation (9) is 0.
The expression of a can be obtained by transforming equation (9):
substituting the expression of a into equation (5) can result in the actual capacitance value of the bus capacitor C being expressed as:
optionally, in this embodiment, the process of determining the aging state of the bus capacitor C according to the actual capacitance value of the bus capacitor C may include the following steps:
obtaining a rated capacitance value of a bus capacitor C;
and calculating the descending amplitude of the capacitance value of the bus capacitor C according to the actual capacitance value and the rated capacitance value of the bus capacitor C.
For example, if the rated capacitance value of the bus capacitor C is 220uF, and the actual capacitance value of the bus capacitor C is 200uF, the capacitance value of the bus capacitor C decreases by (220-.
And determining the aging state of the bus capacitor C according to the descending amplitude of the capacitance value of the bus capacitor C.
As shown in table 1, different types of capacitance value thresholds and aging states corresponding to the bus capacitor C are shown in table 1.
TABLE 1
| State of aging | Aluminum electrolytic capacitor | Metal film capacitor |
| Health care | The reduction amplitude is less than 10 percent | The reduction amplitude is less than 2 percent |
| Aging early warning | The reduction amplitude is more than or equal to 10 percent | The reduction range is more than or equal to 2 percent |
| Fail to work | The reduction range reaches 20 percent | The reduction range reaches 5 percent |
In accordance with the above example, when the bus capacitor C is an aluminum electrolytic capacitor, the capacitance value of the bus capacitor C is decreased by 9%, and it can be seen from the contents shown in table 1 that the aging state of the bus capacitor C is healthy.
In this embodiment, through carrying out on-line monitoring to bus capacitor C among the servo drive circuit, acquire bus capacitor C's actual capacitance value in real time to confirm current bus capacitor C's ageing state according to bus capacitor C's actual capacitance value, just so can carry out the trouble early warning before bus capacitor C appears unusually, thereby realize the comprehensive monitoring to bus capacitor C.
In an optional implementation manner, in this embodiment, after the control circuit calculates the actual capacitance value of the bus capacitor C, the following steps may be further performed:
step a1, a capacitance threshold is obtained.
The capacitance threshold is used for judging whether the bus capacitor C fails or not.
Step a2, determine whether the actual capacitance value of the bus capacitor C is less than the capacitance threshold value.
When the actual capacitance value of the bus capacitor C is smaller than or equal to the capacitance threshold value, the bus capacitor C is invalid, and the servo drive circuit can be shut down protectively in order to avoid uncontrollable loss caused by sudden shutdown of the servo drive circuit.
And when the actual capacitance value of the bus capacitor C is larger than the electrophoresis threshold value, the bus capacitor C is not invalid, and the working personnel can judge the aging state of the bus capacitor C according to the actual capacitance value of the bus capacitor C and judge whether the bus capacitor C needs to be overhauled or not. And under the condition of no external intervention, the servo drive circuit still works normally, and monitors the bus capacitor C again after the preset time of normal work.
Therefore, the actual capacitance value of the bus capacitor C is calculated under the condition that the bus capacitor C does not fail, and after the bus capacitor C fails, the servo drive circuit is subjected to protective shutdown, so that the safety of the servo drive circuit is ensured.
In an embodiment of the present application, as shown in fig. 2, the servo driving circuit further includes a conductive switch K1, the conductive switch K1 is connected in parallel with the charging circuit 102, and a charging resistor R1 is disposed on the charging circuit 102.
In this embodiment, the charging circuit 102 may include a charging switch K2 and a charging resistor R1 connected in series.
Optionally, the process of charging the bus capacitor C by the charging circuit 102 may be: when the bus capacitor C is not failed, the control circuit 101 is powered on, the conductive switch K1 is controlled to be switched off, and the charging switch K2 is switched on, so that the charging circuit 102 is switched on. The bus capacitor C starts to charge through the charging resistor R1. The control circuit 101 can acquire the voltage value of the bus capacitor C in real time through the capacitance detection circuit 104. When the voltage value of the bus capacitor C reaches the working voltage or the voltage value of the bus capacitor C is stable, the control circuit 101 may control the charging switch K2 of the charging circuit 102 to be turned off, and control the conductive switch K1 connected in parallel with the charging circuit 102 to be turned on, then the control circuit 101 may control the power driving circuit 105 to be turned on with the bus capacitor C, and drive the motor to operate, and the servo driving circuit starts to work normally.
Alternatively, the conductive switch K1 may be a relay switch.
In this embodiment, when the power supply directly charges the bus capacitor C, the bus capacitor C is easily broken down by the rapidly increased current, and therefore, when the bus capacitor C is charged, it is necessary to charge the bus capacitor C through the charging resistor R1. When the bus capacitor C is fully charged, the conductive switch K1 is turned on to form a conductive line in order to reduce unnecessary power loss.
When the bus capacitor C is monitored online, the control circuit 101 controls the power driving circuit 105 to stop driving the motor, and then controls the conductive switch K1 to be turned off (at this time, the charging switch K2 in the charging circuit 102 is already in an off state), so that the bus in the servo driving circuit is powered off.
In one embodiment of the present application, as shown in fig. 3, the discharge circuit 103 in the servo drive circuit includes a first discharge circuit 103 and a second discharge circuit 103, wherein the first discharge circuit 103 and the second discharge circuit 103 are respectively connected in parallel with the bus capacitor C.
In an alternative implementation, the first discharge circuit 103 is composed of a relay K3 and a first discharge resistor R2 connected in series with each other, wherein the relay K3 is connected to the control circuit 101, and the first discharge resistor R2 is connected to the bus capacitor C.
The control circuit 101 may send a control signal to relay K3 causing relay K3 to receive power. When the relay K3 receives power, the first discharge resistor R2 can be connected to the bus capacitor C, so that the bus capacitor C can be discharged through the first discharge resistor R2 in the first discharge circuit 103.
In the normal operation process of the servo drive circuit, the first discharge circuit 103 is used for discharging the bus capacitor C when the bus is in overvoltage, so as to reduce the voltage of the bus capacitor C. After the bus voltage is normal, the control circuit 101 controls the relay K3 to be powered off, and the first discharge circuit 103 is in an open state.
When the bus capacitor C is monitored online, the control circuit 101 controls the first discharging circuit 103 to be turned on after the bus capacitor C is fully charged, so as to discharge the bus capacitor C.
In an alternative implementation manner, the second discharge circuit 103 includes a switching transistor T and a second discharge resistor R3 connected in series, where the switching transistor T and the second discharge resistor R3 are respectively connected to the bus capacitor C; the switching transistor T is further connected to the control circuit 101, and is configured to be turned on or off under the control of the control circuit 101.
Optionally, a collector of the switching transistor T is connected to one end of the second discharging resistor R3, an emitter of the switching transistor T is connected to the bus capacitor C, a base set of the switching transistor T is connected to the control circuit 101, and the other end of the second discharging resistor R3 is connected to the bus capacitor C.
In this embodiment, the control circuit 101 may send a control signal to the switching transistor T, so that the switching transistor T is turned on, the bus capacitor C is communicated with the second discharging resistor R3, and the bus capacitor C may discharge through the second discharging resistor R3.
During the normal operation of the servo driving circuit, the control circuit 101 may control the switching transistor T to be turned off, so that the second discharging circuit 103 is in an off state. When the bus is over-voltage, the control circuit 101 discharges the bus capacitor C through the first discharge circuit 103.
When the bus capacitor C is monitored online, the control circuit 101 may control the second discharging circuit 103 to be turned on after the first discharging circuit 103 discharges, that is, the first discharging circuit 103 is used to discharge the bus capacitor C first, and then the second discharging circuit 103 is used to discharge the bus capacitor C.
In an alternative implementation manner, in this embodiment, the resistance value of the first discharge resistor R2 in the first discharge circuit 103 is smaller than the resistance value of the second discharge resistor R3 in the second discharge circuit 103.
Optionally, the second discharge resistor R3 is a low temperature drift resistor.
In an optional implementation manner, when the bus capacitor C is monitored online, the process of discharging the bus capacitor C by the discharge circuit 103 may be: the control circuit 101 controls the first discharging circuit 103 to decrease the voltage of the bus capacitor C to a first target voltage, and then controls the second discharging circuit 103 to decrease the voltage of the bus capacitor C from the first target voltage to a second target voltage.
Specifically, when the bus capacitor C is monitored online, after the bus capacitor C is fully charged, the control circuit 101 first controls the first discharging circuit 103 to be turned on, the second discharging circuit 103 to be turned off, and the bus capacitor C is discharged through the first discharging circuit 103. Meanwhile, the control circuit 101 may control the capacitance detection circuit 104 to acquire a voltage value of the bus capacitance C. When the voltage value of the bus capacitor C decreases from the initial voltage when the bus capacitor C is fully charged to the first target voltage, the control circuit 101 may control the first discharging circuit 103 to be turned off, the second discharging circuit 103 to be turned on, and the bus capacitor C is discharged through the second discharging circuit 103. Meanwhile, the control circuit 101 may control the capacitance detection circuit 104 to acquire a voltage value of the bus capacitance C. When the voltage value of the bus capacitor C decreases from the first target voltage to the second target voltage, the control circuit 101 may control the second discharging circuit 103 to be turned off.
In this embodiment, the second target voltage is less than the first target voltage.
It should be noted that, in this embodiment, in the process that the voltage of the bus capacitor C is dropping, the capacitor detection circuit 104 may collect voltage data of the bus capacitor C according to a preset sampling frequency.
In this embodiment, the first discharging resistor R2 in the first discharging circuit 103 has a larger resistance value, so as to achieve the purpose of quickly reducing the voltage of the bus capacitor C, and the second discharging resistor R3 in the second discharging circuit 103 has a smaller resistance value, so as to slow down the discharging speed of the bus capacitor C. And the second discharge circuit 103 discharges the bus capacitor C by using the low-temperature drift resistor, so that the accuracy of voltage detection of the bus capacitor C is ensured, and the capacitance value estimation error caused by the change of the resistance value along with the temperature change is reduced to the greatest extent, so that the accuracy of the actual capacitance value of the bus capacitor C can be improved.
In one embodiment of the present application, as shown in fig. 4, the capacitance detection circuit 104 includes a first detection resistor R4, a second detection resistor R5, and an isolation amplifier M, wherein the first detection resistor R4 is connected in series with the second detection resistor R5, and the first detection resistor R4 is connected in series with the second detection resistor R5, and then connected across the bus. The isolation amplifier M is connected in parallel with the second detection resistor R5 and is connected to the control circuit 101.
The isolation amplifier M is configured to collect voltage data of the bus capacitor C in the discharging process through the second detection resistor R5, and send the collected voltage data to the control circuit 101.
Optionally, the sum of the resistance of the first detection resistor R4 and the resistance of the second detection resistor R5 is greater than the resistance of the discharge circuit 103.
Optionally, the resistance of the first detection resistor R4 is equal to or proportional to the resistance of the second detection resistor R5.
In this embodiment, the process of the capacitance detection circuit 104 acquiring the voltage of the bus capacitor C may be: the control circuit 101 sends a control signal to the isolation amplifier M, and the isolation amplifier M receives power and acquires the voltage value of the second detection resistor R5. The capacitance detection circuit 104 is connected in parallel with the bus capacitor C, so that the voltage on the capacitance detection circuit 104 is the same as the voltage on the bus capacitor C.
In this embodiment, when the servo driving circuit normally works, the control circuit 101 controls the capacitance detection circuit 104 to collect voltage data of the bus capacitor C, so as to detect whether the bus capacitor C has overvoltage or undervoltage.
When the bus capacitor C is detected on line, the control circuit 101 controls the capacitor detection circuit 104 to collect a plurality of voltage data of the bus capacitor C during the discharging process, and calculates the actual capacitance value of the bus capacitor C according to the collected voltage data.
Optionally, in this embodiment, when the discharge circuit 103 includes the first discharge circuit 103 and the second discharge circuit 103, in order to reduce the data operation amount and improve the accuracy, the control circuit 101 may control the voltage data of the capacitance detection circuit 104 during the discharge of the bus capacitor C through the first discharge circuit 103. It should be noted that the voltage data is only used for monitoring whether the voltage value of the bus capacitor C reaches the first target voltage.
When the bus capacitor C discharges through the second discharging circuit 103, the control circuit 101 may control the capacitor detecting circuit 104 to collect voltage data of the bus capacitor C according to a preset sampling frequency, and store the voltage data. The control circuit 101 may calculate an actual capacitance value of the bus capacitor C according to voltage data collected during the process of discharging the bus capacitor C through the second discharging circuit 103.
Further, in this embodiment, the sum of the resistance of the first detection resistor R4 and the resistance of the second detection resistor R5 is greater than the resistance of the discharge circuit 103, so that the bus capacitor C can be prevented from discharging through the first detection resistor R4 and the second detection resistor R5 of the capacitor detection circuit 104, and the voltage data error of the bus capacitor C detected by the capacitor detection circuit 104 is large, which causes the actual capacitance value of the bus capacitor C to be inaccurate.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A servo drive circuit, characterized by, includes control circuit, charging circuit, bus capacitance, discharge circuit, electric capacity detection circuit and power drive circuit, wherein:
the control circuit is respectively connected with the charging circuit, the discharging circuit, the capacitance detection circuit and the power driving circuit, the charging circuit is connected with the bus capacitor, and the bus capacitor is respectively connected with the discharging circuit, the capacitance detection circuit and the power driving circuit;
the charging circuit is used for charging the bus capacitor under the control of the control circuit, when the bus capacitor is fully charged, the discharging circuit is used for discharging the bus capacitor under the control of the control circuit, the capacitor detection circuit is used for collecting voltage data of the bus capacitor in a discharging process under the control of the control circuit and sending the collected voltage data to the control circuit, the power driving circuit is used for being conducted with the bus capacitor and driving a motor under the control of the control circuit, the control circuit is used for calculating an actual capacitance value of the bus capacitor according to the voltage data collected by the capacitor detection circuit and determining an aging state of the bus capacitor according to the actual capacitance value of the bus capacitor.
2. The servo drive circuit of claim 1, further comprising a conductive switch connected in parallel with the charging circuit, wherein the charging circuit has a charging resistor disposed thereon.
3. The servo drive circuit as claimed in claim 2, wherein the control circuit is configured to control the conductive switch to be turned off and the charging circuit to charge the bus capacitor, and when the bus capacitor is fully charged, the control circuit controls the charging circuit to be turned off and the conductive switch to be turned on.
4. The servo drive circuit of claim 1, wherein the discharge circuit comprises a first discharge circuit and a second discharge circuit, wherein:
the first discharge circuit and the second discharge circuit are respectively connected with the bus capacitor in parallel.
5. The servo driver circuit of claim 4, wherein the resistance of the first discharge circuit is greater than the resistance of the second discharge circuit.
6. The servo drive circuit according to claim 4 or 5, wherein the first discharge circuit comprises a relay and a first discharge resistor connected in series with each other, wherein:
the relay is connected with the control circuit, and the first discharge resistor is connected with the bus capacitor;
and the relay is used for being switched on or switched off under the control of the control circuit.
7. The servo drive circuit according to claim 4 or 5, wherein the second discharge circuit comprises a switching transistor and a second discharge resistor connected in series with each other, wherein:
the switching triode and the second discharge resistor are respectively connected with the bus capacitor;
the switching triode is also connected with the control circuit and used for being switched on or switched off under the control of the control circuit.
8. The servo drive circuit according to claim 4 or 5, wherein the control circuit is configured to control the first discharge circuit to decrease the voltage of the bus capacitor to a first target voltage, and then control the second discharge circuit to decrease the voltage of the bus capacitor from the first target voltage to a second target voltage.
9. Servo driver circuit according to claim 7,
a collector of the switching triode is connected with one end of the second discharge resistor, an emitter of the switching triode is connected with the bus capacitor, and a base set of the switching triode is connected with the control circuit; and the other end of the second discharge resistor is connected with the bus capacitor.
10. The servo drive circuit of claim 1, wherein the capacitance detection circuit comprises a first detection resistor, a second detection resistor, and an isolation amplifier, wherein:
the first detection resistor is connected with the second detection resistor in series, and the isolation amplifier is connected with the second detection resistor in parallel and is connected with the control circuit;
the isolation amplifier is used for acquiring voltage data of the bus capacitor on the second detection resistor in the discharging process and sending the acquired voltage data to the control circuit.
11. The servo drive circuit of claim 10,
the sum of the resistance value of the first detection resistor and the resistance value of the second detection resistor is larger than the resistance value of the discharge circuit.
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| CN202010123076.9A CN111245336A (en) | 2020-02-27 | 2020-02-27 | Servo drive circuit |
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| CN202010123076.9A CN111245336A (en) | 2020-02-27 | 2020-02-27 | Servo drive circuit |
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Application publication date: 20200605 |