CN216387315U - Motor ground fault detection circuit based on frequency converter - Google Patents
Motor ground fault detection circuit based on frequency converter Download PDFInfo
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- CN216387315U CN216387315U CN202122778930.8U CN202122778930U CN216387315U CN 216387315 U CN216387315 U CN 216387315U CN 202122778930 U CN202122778930 U CN 202122778930U CN 216387315 U CN216387315 U CN 216387315U
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Abstract
The utility model discloses a motor ground fault detection circuit based on a frequency converter, which relates to the field of electronic circuits and comprises an operational amplifier circuit, a level comparison circuit, an output clamping circuit and a CPU (central processing unit), wherein the operational amplifier circuit, the level comparison circuit, the output clamping circuit and the CPU are sequentially connected, three-phase current passes through a current transformer and then outputs voltage signals to the operational amplifier circuit, the voltage signals are added by the operational amplifier circuit and are inverted to output corresponding voltage values, the level comparison circuit outputs corresponding level signals according to whether the voltage values are within a first preset voltage range, the output clamping circuit is used for clamping the level signals within a second preset voltage range and outputting the level signals to the CPU, and the CPU controls the on-off of PWM (pulse width modulation) signals according to the received level signals. The detection circuit plays a role in cutting off the output of the frequency converter to the motor with the ground fault and providing warning for field personnel, can be applied to the frequency converter, can also be applied to motor driving devices such as a servo motor and the like, and has good application prospect.
Description
Technical Field
The utility model relates to the field of electronic circuits, in particular to a motor ground fault detection circuit based on a frequency converter.
Background
Among the various industrial personal computer power devices, the motor is one of the most commonly used components. However, as the service life increases, the motor may have a ground fault due to damage, deterioration of insulation, breakage of cables, or faulty wiring. At this moment, not only can influence the normal operating of motor, more likely harm operating personnel's personal safety.
If the frequency converter contains a grounding fault detection circuit, the output of the driver can be stopped, and accidents can be effectively avoided, so that the functional circuit has wide application prospect.
SUMMERY OF THE UTILITY MODEL
The present invention provides a frequency converter-based ground fault detection circuit for a motor, which aims at the above problems and technical requirements.
The technical scheme of the utility model is as follows:
a motor ground fault detection circuit based on a frequency converter comprises an operational amplifier circuit, a level comparison circuit, an output clamping circuit and a CPU which are sequentially connected, wherein three-phase current outputs voltage signals to the operational amplifier circuit after passing through a current transformer, the voltage signals are added by the operational amplifier circuit and are inverted to output corresponding voltage values, the level comparison circuit outputs corresponding level signals according to whether the voltage values are within a first preset voltage range, the output clamping circuit is used for clamping the level signals within a second preset voltage range and outputting the level signals to the CPU, and the CPU controls the on-off of PWM signals according to the received level signals.
The operational amplifier circuit comprises an operational amplifier, five resistors and a first capacitor, wherein the inverting input end of the operational amplifier is respectively connected with the first ends of the first resistor to the fourth resistor and the first end of the first capacitor, the second ends of the first resistor to the third resistor are used as the three-phase input end of the operational amplifier circuit to respectively receive voltage signals, the second end of the fourth resistor and the second end of the first capacitor are connected with the output end of the operational amplifier, the non-inverting input end of the operational amplifier circuit is grounded through the fifth resistor, and the output end of the operational amplifier circuit is connected with the input end of the level comparison circuit.
The further technical scheme is that the level comparison circuit comprises a first level comparator, a second level comparator, seven resistors, two capacitors and two clamping diodes, wherein the inverting input end of the first level comparator is respectively connected with the first ends of the sixth resistor and the seventh resistor, the second end of the sixth resistor is connected with a first power supply, the non-inverting input end of the first level comparator is respectively connected with the first ends of the eighth resistor and the ninth resistor, the second end of the eighth resistor is used as the input end of the level comparison circuit to receive the voltage value output by the operational amplification circuit, the second end of the ninth resistor is connected with the anode of the first clamping diode, the second capacitor is connected between the non-inverting input end and the inverting input end of the first level comparator, the inverting input end of the second level comparator is connected with the second end of the eighth resistor, the non-inverting input end of the second level comparator is respectively connected with the first ends of the tenth resistor to the twelfth resistor, the second end of the tenth resistor is connected with the second power supply, the second end of the twelfth resistor is connected with the anode of the second clamping diode, the second ends of the seventh resistor and the eleventh resistor are grounded, a third capacitor is connected between the non-inverting input end and the inverting input end of the second level comparator, the output ends of the first level comparator and the second level comparator, the clamped ends of the first clamping diode and the second clamping diode are connected, the connected end is used as the output end of the level comparator circuit to be connected with the input end of the output clamping circuit, and the connected end is further connected with the second power supply through the thirteenth resistor.
The output clamping circuit comprises a third clamping diode, three resistors and a fourth capacitor, wherein the first end of the fourteenth resistor is used as the input end of the output clamping circuit to receive a level signal output by the level comparison circuit, the second end of the fourteenth resistor is connected with the first end of the fifteenth resistor through the clamped end of the third clamping diode, the second end of the fifteenth resistor is used as the output end of the output clamping circuit to be connected with the CPU, the sixteenth resistor is connected between the clamped end and the cathode of the third clamping diode in parallel, the fourth capacitor is connected between the clamped end and the anode of the third clamping diode in parallel, and the cathode of the third clamping diode is connected with a third power supply and the anode is grounded.
The further technical scheme is that the motor ground fault detection circuit also comprises an alarm device connected with the CPU.
The further technical scheme is that the operational amplifier is realized based on a BA10358F model.
The further technical scheme is that the first level comparator and the second level comparator are realized based on an LM293DR2 model, and the first clamping diode and the second clamping diode are realized based on a BAV99W model.
The further technical scheme is that the third clamping diode is realized based on a BAV99W model.
The beneficial technical effects of the utility model are as follows:
the three-phase current of the motor is input into the motor ground fault detection circuit, the level comparison circuit is used for detecting whether the three-phase current is balanced or not, the CPU further controls the on-off of the PWM signal according to the level signal output by the level comparison circuit, namely after the motor has ground fault and the RUN machine, the vector sum of the three-phase current is not zero, the output voltage value is not within a first preset voltage range, the CPU cuts off the PWM signal output and controls the alarm device to display a ground fault alarm to remind field workers to check the ground fault, and the detection circuit has good application prospect.
Drawings
Fig. 1 is a circuit diagram of a frequency converter-based motor ground fault detection circuit provided in the present application.
Detailed Description
The following further describes the embodiments of the present invention with reference to the drawings.
As shown in fig. 1, a frequency converter-based motor ground fault detection circuit includes an operational amplifier circuit, a level comparator circuit, an output clamp circuit and a CPU (not shown in the figure) connected in sequence. Optionally, an alarm device (not shown) connected to the CPU is also included. The three-phase current outputs voltage signals IU, IV and IW to an operational amplifier circuit after passing through a current transformer, corresponding voltage values are output after the voltage signals IU, IV and IW are added and inverted by the operational amplifier circuit, a level comparison circuit outputs corresponding level signals according to whether the voltage values are in a first preset voltage range, an output clamping circuit is used for clamping the level signals in a second preset voltage range and outputting the level signals to a CPU, and the CPU controls the on-off of PWM signals and an alarm device according to the received level signals.
The operational amplifier circuit comprises an operational amplifier IC1, five resistors and a first capacitor C1, wherein the inverting input end of the operational amplifier IC1 is respectively connected with the first ends of the first resistor R1 to the fourth resistor R4 and the first end of the first capacitor C1, the second ends of the first resistor R1 to the third resistor R3 are used as the three-phase input end of the operational amplifier circuit IC1 to respectively receive voltage signals IU, IV and IW, the second end of the fourth resistor R4 and the second end of the first capacitor C1 are connected with the output end of the operational amplifier IC1, the non-inverting input end of the operational amplifier circuit IC1 is grounded through the fifth resistor R5, and the output end of the operational amplifier circuit IC1 is connected with the input end of the level comparison circuit.
Optionally, the operational amplifier IC1 is implemented based on a BA10358F model with a power supply of-15V to 15V.
The operational amplifier circuit IC1 outputs a voltage value U ═ 7.5/15 × (U)IU+UIV+UIW) Wherein (U)IU+UIV+UIW) The voltage value is the voltage value corresponding to the sum of the three-phase currents after passing through the current transformer.
The level comparison circuit comprises a first level comparator IC2A, a second level comparator IC2B, seven resistors, two capacitors and two clamping diodes, wherein the inverting input end of the first level comparator IC2A is respectively connected with the first ends of a sixth resistor R6 and a seventh resistor R7, the second end of the sixth resistor R6 is connected with a first power supply-15V, the non-inverting input end of the first level comparator IC2A is respectively connected with the first ends of an eighth resistor R8 and a ninth resistor R9, the second end of an eighth resistor R8 serves as the input end of the level comparison circuit to receive the voltage value U output by the operational amplifier circuit, the second end of the ninth resistor R9 is connected with the anode of a first clamping diode D1, a second capacitor C2 is connected between the non-inverting input end and the inverting input end of the first level comparator IC2A, the inverting input end of the second level comparator IC2B is connected with the second end of the eighth resistor R8, the non-inverting input end of the second level comparator IC2B is respectively connected with the twelfth resistor R10 to the twelfth end of the twelfth resistor R12, a second end of the tenth resistor R10 is connected to the second power supply +15V, a second end of the twelfth resistor R12 is connected to the anode of the second clamping diode D2, second ends of the seventh resistor R7 and the eleventh resistor R11 are grounded, a third capacitor C3 is connected between the non-inverting input terminal and the inverting input terminal of the second level comparator IC2B, output terminals of the first level comparator IC2A and the second level comparator IC2B, clamped terminals of the first clamping diode D1 and the second clamping diode D2 are connected, the connection terminal is used as an output terminal of the level comparator circuit and is connected to an input terminal of the output clamping circuit, and the connection terminal is further connected to the second power supply +15V through the thirteenth resistor R13.
Optionally, the first and second level comparators IC2A and IC2B are implemented based on the model LM293DR2, and the first and second clamping diodes D1 and D2 are implemented based on the model BAV 99W.
The voltage U at the non-inverting input terminal of the second level comparator IC2B is obtained by dividing the voltage U by the sixth resistor R6, the seventh resistor R7, the ninth resistor R9 and the tenth resistor R10B＝15V×[1K/(1K+13K)]1.07V, inverting input U of first level comparator IC2AA＝-15V×[1K/(1K+13K)]And the value is approximately equal to-1.07V. When the voltage value U output by the operational amplifier circuit IC1 is greater than 1.07V or less than-1.07V, the level comparator circuit outputs a low level signal.
The output clamp circuit comprises a third clamp diode D3, three resistors and a fourth capacitor C4, wherein a first end of a fourteenth resistor R14 serves as an input end of the output clamp circuit to receive a level signal output by the level comparison circuit, a second end of the fourteenth resistor R14 is connected with a first end of a fifteenth resistor R15 through a clamped end of the third clamp diode D3, a second end of a fifteenth resistor R15 serves as an output end GF of the output clamp circuit to be connected with the CPU, a sixteenth resistor R16 is connected between the clamped end and a cathode of the third diode clamp D3 in parallel, a fourth capacitor C4 is connected between the clamped end and an anode of the third clamp diode D3 in parallel, and a cathode of the third clamp diode D3 is connected with a third power supply DVCC and an anode is grounded. The third clamping diode D3 clamps the output at (V)GND+VF) To (V)DVCC-VF) To protect the subsequent stage circuit, wherein VGNDIs 0V, VDVCCIs 5V.
Optionally, the third clamping diode D3 is implemented based on BAV99W model.
Provided by the present applicationThe principle of the motor ground fault detection circuit is as follows: when the three-phase currents are balanced, the vector sum of the three-phase currents is zero, i.e. (I)IU+IIV+IIW) 0, i.e. (U)IU+UIV+UIW) 0. When the motor has ground fault and RUNs, the current transformers output voltage signals IU, IV and IW, the voltage signals are added through the operational amplifier, if the vector sum is not equal to 0 and exceeds a first preset voltage range of the level comparison circuit (namely more than 1.07V or less than-1.07V, the range is 50% of rated output current of the frequency converter, the level can be adjusted according to field requirements during actual application), and the level comparison circuit outputs low level, the CPU cuts off PWM signal output and controls the alarm device to display ground fault alarm to remind field workers to investigate the ground fault.
In summary, the detection circuit plays a role in cutting off the output of the frequency converter to the motor with the ground fault and providing warning for field personnel, and the detection circuit can be applied to the frequency converter, can also be applied to motor driving devices such as a servo motor and the like, and has a good application prospect.
What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiment. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and concept of the present invention are to be considered as included within the scope of the present invention.
Claims (8)
1. A motor ground fault detection circuit based on a frequency converter is characterized by comprising an operational amplifier circuit, a level comparison circuit, an output clamping circuit and a CPU which are sequentially connected, wherein three-phase current passes through a current transformer and then outputs voltage signals to the operational amplifier circuit, the voltage signals are added by the operational amplifier circuit and are reversely output corresponding voltage values, the level comparison circuit outputs corresponding level signals according to whether the voltage values are within a first preset voltage range, the output clamping circuit is used for clamping the level signals within a second preset voltage range and outputting the level signals to the CPU, and the CPU controls the on-off of PWM signals according to the received level signals.
2. The frequency converter-based motor ground fault detection circuit according to claim 1, wherein the operational amplifier circuit comprises an operational amplifier, five resistors and a first capacitor, the inverting input terminals of the operational amplifier are respectively connected to the first terminals of the first to fourth resistors and the first terminal of the first capacitor, the second terminals of the first to third resistors are respectively used as the three-phase input terminals of the operational amplifier circuit to receive the voltage signal, the second terminals of the fourth resistor and the first capacitor are connected to the output terminal of the operational amplifier, the non-inverting input terminal of the operational amplifier circuit is grounded through the fifth resistor, and the output terminal of the operational amplifier circuit is connected to the input terminal of the level comparison circuit.
3. The frequency converter-based motor ground fault detection circuit according to claim 1, wherein the level comparison circuit comprises a first level comparator, a second level comparator, seven resistors, two capacitors and two clamping diodes, the inverting input terminal of the first level comparator is connected to the first terminals of a sixth resistor and a seventh resistor, respectively, the second terminal of the sixth resistor is connected to the first power supply, the non-inverting input terminal of the first level comparator is connected to the first terminals of an eighth resistor and a ninth resistor, respectively, the second terminal of the eighth resistor is used as the input terminal of the level comparison circuit to receive the voltage value outputted from the operational amplifier circuit, the second terminal of the ninth resistor is connected to the anode of the first clamping diode, the second capacitor is connected between the non-inverting input terminal and the inverting input terminal of the first level comparator, and the inverting input terminal of the second level comparator is connected to the second terminal of the eighth resistor, the non-inverting input end of the second level comparator is connected with first ends of a tenth resistor and a twelfth resistor respectively, the second end of the tenth resistor is connected with a second power supply, the second end of the twelfth resistor is connected with the anode of a second clamping diode, second ends of the seventh resistor and the eleventh resistor are grounded, a third capacitor is connected between the non-inverting input end and the inverting input end of the second level comparator, output ends of the first level comparator and the second level comparator and clamped ends of the first clamping diode and the second clamping diode are connected, a connecting end is used as an output end of the level comparator circuit to be connected with an input end of the output clamping circuit, and the connecting end is further connected with the second power supply through a thirteenth resistor.
4. The frequency converter-based motor ground fault detection circuit of claim 1, wherein the output clamp circuit comprises a third clamp diode, three resistors and a fourth capacitor, a first end of a fourteenth resistor is used as an input end of the output clamp circuit to receive the level signal output by the level comparison circuit, a second end of the fourteenth resistor is connected to a first end of a fifteenth resistor through a clamped end of the third clamp diode, a second end of the fifteenth resistor is used as an output end of the output clamp circuit to be connected to the CPU, a sixteenth resistor is connected in parallel between the clamped end and a cathode of the third clamp diode, the fourth capacitor is connected in parallel between the clamped end and an anode of the third clamp diode, and a cathode of the third clamp diode is connected to a third power supply and an anode is connected to ground.
5. The frequency converter-based motor ground fault detection circuit of any one of claims 1-4, further comprising an alarm device connected to the CPU.
6. The frequency converter-based motor ground fault detection circuit of claim 2, wherein the operational amplifier is implemented based on a BA10358F model.
7. The frequency converter-based motor ground fault detection circuit of claim 3, wherein the first and second level comparators are implemented based on model LM293DR2, and the first and second clamping diodes are implemented based on model BAV 99W.
8. The frequency converter-based motor ground fault detection circuit of claim 4, wherein the third clamping diode is implemented based on BAV99W model.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122778930.8U CN216387315U (en) | 2021-11-09 | 2021-11-09 | Motor ground fault detection circuit based on frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122778930.8U CN216387315U (en) | 2021-11-09 | 2021-11-09 | Motor ground fault detection circuit based on frequency converter |
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| Publication Number | Publication Date |
|---|---|
| CN216387315U true CN216387315U (en) | 2022-04-26 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122778930.8U Active CN216387315U (en) | 2021-11-09 | 2021-11-09 | Motor ground fault detection circuit based on frequency converter |
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| Country | Link |
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| CN (1) | CN216387315U (en) |
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2021
- 2021-11-09 CN CN202122778930.8U patent/CN216387315U/en active Active
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