CN215580353U - Frequency conversion controller protection circuit and motor frequency conversion control system - Google Patents
Frequency conversion controller protection circuit and motor frequency conversion control system Download PDFInfo
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- CN215580353U CN215580353U CN202121660734.4U CN202121660734U CN215580353U CN 215580353 U CN215580353 U CN 215580353U CN 202121660734 U CN202121660734 U CN 202121660734U CN 215580353 U CN215580353 U CN 215580353U
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Abstract
The utility model provides a frequency conversion controller protection circuit and a motor frequency conversion control system, which comprise: the input end of the rectifying circuit is suitable for being connected with an alternating current power supply, the variable frequency controller is suitable for being connected between the output end of the rectifying circuit and the voltage holding circuit, and when a voltage signal acquired from the voltage holding circuit is larger than a preset threshold value, the voltage input of the variable frequency controller is cut off. The utility model can monitor the high-voltage pulse condition generated at the input end of the variable-frequency controller when the alternating-current 220V generator is used as a power supply, thereby protecting the variable-frequency controller through the controller.
Description
Technical Field
The utility model relates to the technical field of circuits, in particular to a frequency conversion controller protection circuit and a motor frequency conversion control system.
Background
Problems typically do not arise when power tools including a non-inductive brushless permanent magnet motor without a large electrolytic capacitor are powered using an ac power grid. However, when the electric tool uses the ac 220V generator as a power supply, the variable frequency controller may be damaged by the high voltage pulse input by the ac 220V generator, and at this time, the ac 220V generator may have the high voltage pulse to the input end of the variable frequency controller, which may exceed the withstand voltage of the components of the variable frequency controller, thereby damaging the variable frequency controller. Because the frequency converter enters a chopping output state, the voltage pulse change frequency is high, and a detection method for detecting the input voltage of the frequency conversion controller is generally used, so that the high-voltage pulse which changes rapidly cannot be effectively monitored.
SUMMERY OF THE UTILITY MODEL
The problem to be solved by the utility model is how to monitor the overvoltage signal at the input end of the variable frequency controller in time.
In order to solve the above problems, the present invention provides a protection circuit for a variable frequency controller, comprising:
the input end of the rectifying circuit is suitable for being connected with an alternating current power supply, the variable frequency controller is suitable for being connected between the output end of the rectifying circuit and the voltage holding circuit, and when a voltage signal acquired from the voltage holding circuit is larger than a preset threshold value, the voltage input of the variable frequency controller is cut off.
Optionally, the voltage holding circuit includes a diode and a first capacitor, an anode of the diode is connected to the output end of the rectifying circuit, a cathode of the diode is connected to an anode of the first capacitor, and a cathode of the first capacitor is grounded.
Optionally, the protection circuit of the variable frequency controller further includes a buck filter circuit, and the buck filter circuit is connected to the voltage holding circuit to collect the voltage signal.
Optionally, the step-down filter circuit includes a plurality of step-down resistors and a second capacitor, the plurality of step-down resistors are connected in series, one end of each step-down resistor is connected between the diode and the first capacitor, the other end of each step-down resistor is grounded, the second capacitor is connected in parallel with at least one step-down resistor, and the voltage signal is collected from the connection end of the second capacitor and the step-down resistor.
Optionally, the protection circuit of the frequency conversion controller further includes a temperature-sensitive resistor, and the temperature-sensitive resistor is disposed between the output end of the rectification circuit and the voltage holding circuit.
Optionally, the rectifier circuit includes a rectifier bridge and a filter capacitor, an input end of the rectifier bridge is adapted to be connected to the ac power supply, and an output end of the rectifier bridge is connected to the voltage holding circuit through the filter capacitor.
Optionally, the rectifier circuit further includes a fuse device, and the fuse device is disposed on a live wire of the input end of the rectifier bridge.
Optionally, the protection circuit of the frequency conversion controller further includes a low-voltage apparatus power supply port, and the low-voltage apparatus power supply port is disposed between the diode and the first capacitor.
Optionally, the protection circuit of the variable frequency controller further includes a controller, and the controller is configured to obtain the voltage signal.
On the other hand, the utility model also provides a motor variable frequency control system, which comprises an alternating current power supply, a variable frequency controller and the variable frequency controller protection circuit.
Compared with the prior art, the motor variable frequency control system has the same advantages as the variable frequency controller protection circuit, and is not described again here.
According to the utility model, the voltage holding circuit arranged in the frequency conversion controller protection circuit is used for holding the high-voltage pulse signal appearing in the circuit in the voltage holding circuit, so that the high-voltage pulse signal is monitored, and when the monitored voltage signal is greater than a preset threshold value, the voltage input of the frequency conversion controller is cut off, so that the elements of the frequency conversion controller are protected, and the frequency conversion controller is prevented from being damaged by the high-voltage pulse generated by the 220V alternating-current generator.
Drawings
FIG. 1 is a schematic diagram of a protection circuit of a frequency conversion controller according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a protection circuit of the variable frequency controller according to the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
When the electric tool is driven by the non-inductive brushless permanent magnet motor without a large electrolytic capacitor, two voltage input modes can be selected: firstly, an alternating current power grid is used as a power supply, namely, a variable frequency controller is connected to the power grid to work; and secondly, an alternating current 220V generator is used as a power supply, namely, the variable frequency controller is directly connected with the alternating current 220V generator to work.
When the alternating current power grid is used for supplying power, because the power capacity of the alternating current power grid is large, under the condition that the variable frequency controller works, the output of the alternating current power grid to the variable frequency controller is far larger than the maximum power of the variable frequency controller, the power supply voltage is very stable, and the fluctuation in power generally can not occur, so that the variable frequency controller can not generate the fluctuation in voltage during the whole acting period and can normally work.
However, when an ac 220V generator is used as a power supply of the inverter controller, there are two cases:
firstly, when the input power of the alternating current 220V generator to the variable frequency controller does not exceed the rated power of the variable frequency controller, the variable frequency controller is in a non-chopping state and can normally work, the circuit has no fluctuation in power, and the alternating current 220V generator also correspondingly stably works without abnormal conditions.
Secondly, when the output power of the alternating current 220V generator is larger than the rated power of the variable frequency controller, the variable frequency controller enters a chopping state from a normal working state, and the voltage is output in a chopping form, at the moment, because the variable frequency controller does not have a large electrolytic capacitor to store extra electric energy, the output power in the chopping state can only be provided by the generator in real time, the output power of the variable frequency controller can be instantly reduced to 0 at the same moment when entering the chopping state, because the power generation principle of the alternating current 220V generator (the conductor period cuts the magnetic induction line to form alternating current) enables the generator not to protect the variable frequency controller by synchronously turning off the output, because of the power generation principle of the alternating current generator, the output power and the voltage of the alternating current 220V generator have certain hysteresis compared with the load power and the load voltage, therefore, when the variable frequency controller enters the chopping state, the alternating current 220V generator can output a short-time high-voltage pulse, so that an abnormal high-voltage pulse appears at the input end of the variable frequency controller, and when the voltage value of the high-voltage pulse exceeds the withstand voltage value of the internal elements of the variable frequency controller, the variable frequency controller can be damaged.
As shown in fig. 1, a protection circuit of a frequency conversion controller according to an embodiment of the present invention includes: the input end of the rectifying circuit is suitable for being connected with an alternating current power supply, the variable frequency controller is suitable for being connected between the output end of the rectifying circuit and the voltage holding circuit, and when a voltage signal acquired from the voltage holding circuit is larger than a preset threshold value, the voltage input of the variable frequency controller is cut off.
The high-voltage electrical apparatus power supply port BUS is the inverter controller power supply, also is connected to power device and provides the power, when the voltage that inverter controller chopper output caused because the 220V generator brought is unusual, can produce unusual high-voltage pulse at high-voltage electrical apparatus power supply port BUS point, endangers inverter controller.
Because the inverter controller needs direct current input, before the inverter controller is connected, alternating current is converted into direct current through the rectifying circuit and is used as power supply for the inverter controller. The voltage holding circuit is used for holding a high-voltage signal in the circuit, and ensures that the high-voltage pulse signal in the circuit can be monitored more easily. When the voltage signal collected by the voltage holding circuit is greater than the preset threshold value, the input of the variable frequency controller is turned off, so that the voltage signal is prevented from being too large and exceeding the withstand voltage value of an element of the variable frequency controller, and the variable frequency controller is protected from being damaged by high voltage.
Since the input voltage of the inverter controller needs to be lower than the rated voltage, if the input voltage is higher than the withstand voltage of the internal components of the inverter controller, the inverter controller may be damaged. When the voltage in the circuit abnormally rises, the voltage holding circuit can effectively capture and hold a high-voltage signal in the circuit, if the high-voltage signal is higher than the rated voltage of the variable-frequency controller, the high-voltage signal can damage elements in the variable-frequency controller, so the variable-frequency controller is connected with the input of the voltage holding circuit, and the input voltage of the variable-frequency controller cannot be influenced by the high-voltage signal held by the voltage holding circuit. In addition, since the inverter controller needs to be driven by a dc voltage, the inverter controller needs to be provided between the voltage holding circuit and the output terminal of the rectifier circuit, and the dc power output from the rectifier circuit is input as a power supply to the inverter controller.
The structure of the voltage holding circuit can ensure that the high-voltage pulse which rises instantly is monitored, and once the voltage holding circuit collects the abnormal high-voltage pulse which is higher than a preset threshold value, the voltage input of the frequency conversion controller is cut off so as to protect the elements of the frequency conversion controller.
Optionally, the voltage holding circuit includes a diode and a first capacitor, an anode of the diode is connected to the output end of the rectifying circuit, a cathode of the diode is connected to an anode of the first capacitor, and a cathode of the first capacitor is grounded.
As shown in fig. 1, for convenience of distinction and description, the diode of the voltage holding circuit is referred to as a first diode D13, and the capacitor connected to the first diode D13 in the voltage holding circuit is referred to as a first capacitor EC 2.
The positive pole of the first diode D13 is connected with the output end of the rectifying circuit, the frequency conversion controller is also connected with the output end of the rectifying circuit, the input voltage of the first diode D13 can be ensured to be consistent with the input voltage change condition of the frequency conversion controller, and the voltage at the two ends of the first diode D13 can be ensured to be consistent with the input voltage fluctuation condition of the frequency conversion controller.
In one embodiment, the first capacitor EC2 is connected to the cathode of the first diode D13, when the output power of the ac 220V generator is smaller than the rated power of the inverter controller, the current passing through the first diode D13 flows from the anode to the cathode, the first diode D13 is turned on, the first capacitor EC2 is in a charging state until the charge on the anode of the first capacitor EC2 tends to be stable, when the power of the ac 220V generator exceeds the rated power of the inverter controller, the inverter controller enters a chopping state, the generator outputs a high voltage pulse, the voltage in the circuit becomes high, the current passing through the first diode D13 flows from the anode to the cathode, the first diode D13 is turned on, the voltage between the first capacitor EC2 and the first diode D13 also rises synchronously, and the first capacitor EC2 starts to change from the stable state to the charging state. The high-voltage pulse output by the generator is very short, the voltage is recovered to be normal in a short time, at the moment, the voltage input by the anode of the first diode D13 is changed from high to low, the first diode D13 is cut off in the reverse direction, the current cannot pass through the diode D13, the fully charged first capacitor EC2 cannot be discharged smoothly due to the fact that the cathode of the first diode D13 is connected with the first capacitor EC2, the charge between the fully charged first capacitor EC2 and the fully charged first capacitor D13 is effectively kept, the voltage between the first capacitor EC2 and the first diode D13 can be effectively kept, at the moment, voltage detection is carried out on the low-voltage electric appliance power supply port BUS1 shown in the figure 1 by using a voltage measuring tool, and the voltage abnormality of the low-voltage electric appliance power supply port BUS1 can be timely monitored.
Optionally, the first capacitor EC2 is a 10 μ F/400V capacitor, and the first diode D13 is an S3M patch diode.
Optionally, the protection circuit of the variable frequency controller further includes a buck filter circuit, and the buck filter circuit is connected to the voltage holding circuit to collect the voltage signal.
As shown in fig. 1, in an embodiment, the voltage-reducing filter circuit includes a voltage-reducing circuit and a filter circuit, the voltage-reducing circuit is used to reduce the voltage in the circuit and ensure that it is easy to collect a varying voltage signal, and on the other hand, the voltage is reduced to a certain range and used as the input of a low-voltage electrical appliance to ensure that the electrical appliance is not damaged by a high voltage; the filter circuit is used for further stabilizing the direct-current voltage, keeping direct-current components in the direct-current voltage as much as possible, reducing alternating-current components and smoothing voltage wave deformation.
Optionally, the step-down filter circuit includes a plurality of step-down resistors and a second capacitor, the plurality of step-down resistors are connected in series, one end of each step-down resistor is connected between the diode and the first capacitor, the other end of each step-down resistor is grounded, the second capacitor is connected in parallel with at least one step-down resistor, and the voltage signal is collected from the connection end of the second capacitor and the step-down resistor.
In one embodiment, the plurality of step-down resistors includes a resistor R16, a resistor R19, a resistor R22, and a resistor R25. The second capacitance is named second capacitance C14.
The resistor R16, the resistor R19 and the resistor R22 are connected in series and form a voltage division circuit with the resistor R25, so that the voltage of the VDC is kept between 3V and 5V, and the voltage signal changing in the circuit is easy to acquire and monitor. Meanwhile, the voltage of 3V-5V is also used for being input into other low-voltage electric appliances to be used as the input voltage of the low-voltage electric appliances.
In an embodiment, as shown in fig. 1, the resistor R16, the resistor R19, and the resistor R22 are connected in series, and form a low-pass filter circuit with the second capacitor C14, and are connected to the input of the rectifier circuit through the live wire L and the zero wire N, so as to be used as a power supply of the frequency conversion controller protection circuit of the high-frequency pulse voltage signal detection circuit, the dc voltage output by the rectifier circuit is input to the voltage holding circuit and the voltage reduction filter circuit, the ac voltage is rectified into dc through the rectifier circuit and is used as the power supply of the frequency conversion controller, and the dc voltage is also input to the subsequent voltage holding circuit to realize the monitoring of the high-frequency pulse voltage, and the dc voltage is input to the low-pass filter circuit to further stabilize the dc voltage, reduce the ac component in the pulsating dc voltage, and retain the dc component as the input voltage of the VDC.
Optionally, the protection circuit of the frequency conversion controller further includes a temperature-sensitive resistor, and the temperature-sensitive resistor is disposed between the output end of the rectification circuit and the voltage holding circuit.
Optionally, the temperature-sensitive resistor is an MS32-10015 temperature-sensitive resistor.
The temperature sensitive resistor is connected with the output of the rectifying circuit and is connected with the anode of the first diode D13, the cathode of the first diode D13 is connected with the first capacitor EC2, in the embodiment, the temperature sensitive resistor is an NTC temperature sensitive resistor which has a large resistance at a low temperature and a small resistance at a high temperature and is used for providing temperature detection and compensation.
Optionally, the rectifier circuit includes a rectifier bridge and a filter capacitor, an input end of the rectifier bridge is adapted to be connected to the ac power supply, and an output end of the rectifier bridge is connected to the voltage holding circuit through the filter capacitor.
For ease of distinction and description, the filter capacitances are referred to as capacitance C4 and capacitance C5, respectively.
Optionally, the capacitor C4 and the capacitor C5 are both 684J630V capacitors.
The input alternating current is conducted in a single direction through the diodes in the rectifier bridge, and by utilizing the single-direction conduction characteristic of the diodes, alternating current voltage is converted into single-direction direct current pulsating voltage due to the fact that the diodes work in pairs, and rectification work of converting the alternating current into direct current is completed.
In an embodiment, a capacitor C4 and a capacitor C5 are connected in parallel at a dc end of a rectifier bridge, and since the rectifier bridge utilizes the unidirectional conduction characteristic of a diode, alternating current which changes periodically passes through a diode opposite to the rectifier bridge in a unidirectional manner to form continuously changing pulsating voltage, but a loss voltage drop occurs in the voltage after passing through the rectifier bridge, that is, the output voltage is slightly lower than the input voltage, after the dc end is connected in parallel with a second capacitor, charging can be performed when the voltage rises, discharging can be performed when the voltage falls, the peak of the dc voltage is compressed, and the valley of the dc voltage is filled.
Because the frequency conversion controller and the single chip microcomputer both need direct current as input, the rectifying circuit is directly connected with a power supply and used as the power supply input of the subsequent frequency conversion controller and the single chip microcomputer or other power devices.
Optionally, the rectifier circuit further includes a safety device, and the safety device is disposed on the live line L at the input end of the rectifier bridge.
In an embodiment, the frequency-conversion controller protection circuit of the high-frequency pulse voltage signal detection circuit is further provided with a fuse FU1 which can be fused when the current of the circuit is abnormally increased to a certain height, so that the circuit is protected from being damaged by a large current or a fire or components.
Optionally, the protection circuit of the frequency conversion controller further includes a low-voltage apparatus power supply port, and the low-voltage apparatus power supply port is disposed between the diode and the first capacitor.
The low-voltage apparatus power supply port BUS1 is a low-power low-voltage power supply BUS, and is disposed between the first diode D13 and the first capacitor EC2, and is used for obtaining the voltage held by the first diode D13 and the first capacitor EC 2.
Optionally, the protection circuit of the variable frequency controller further includes a controller, and the controller is configured to obtain the voltage signal.
220V alternating current input by a zero line and a live line is converted into high-voltage (about 310V) direct current through a rectifying circuit, then the high-voltage direct current is converted into low-voltage direct current (3V-5V) through a voltage division circuit consisting of a resistor R16, a resistor R19, a resistor R22 and a resistor R25, and then the low-voltage direct current is further filtered through a filter capacitor C14 in the circuit, so that the direct current component is reserved, and more stable direct current is output and is used as the input of a controller.
Optionally, the controller includes an MCU, an ARM, a DSP, a CPLD, an FPGA, and the like.
In one embodiment, the VDC is input to a controller such as a single chip, the single chip is used to monitor the voltage of the protection circuit of the variable frequency controller, and when abnormal voltage pulses occur in the protection circuit, the single chip is used to protect the circuit, such as cutting off the power supply of the variable frequency controller, so as to protect the components of the variable frequency controller from being damaged by the high voltage pulses.
In an embodiment, when the variable frequency controller is connected to an ac power grid, the ac power grid is used as a power source, and since the power capacity of the ac power grid is large and the power is much greater than the rated power of the variable frequency controller, the voltage is stable when the variable frequency controller is connected to the ac power grid and is maintained at 220V, so that no abnormal condition occurs, the voltage between the first diode D13 and the first capacitor EC2 is always stable at 220V, and no high-voltage pulse occurs in the circuit.
In another embodiment, as shown in fig. 2, when an ac 220V generator is used as an input power source of the inverter controller and the output power of the generator is greater than the rated power of the inverter controller, the inverter controller is operated in an overload mode, the output of the inverter controller is changed into a chopping output, and at the time when the output is changed into the chopping output, the inverter controller does not have a large electrolytic capacitor, so that the output power of the inverter controller is completely provided by the generator, and at this time, since the power of the inverter controller is instantly reduced to 0, since the generator cannot be synchronously turned off, a large pulse voltage is generated by the generator. At the moment, the high-voltage pulse enters the frequency conversion controller protection circuit of the utility model, is rectified into direct-current voltage by the rectifying circuit, then provides voltage for the frequency conversion controller and other power devices connected with the power supply port BUS of the high-voltage electrical apparatus through the power supply port BUS of the high-voltage electrical apparatus, and when the high-voltage pulse is higher than the withstand voltage value of elements in the circuit, the electrical apparatus can be damaged.
When the high-voltage pulse passes through a power supply port BUS of a high-voltage electric appliance, the high-voltage pulse also enters a voltage holding circuit through a first diode D13, due to the fact that the voltage is increased, the first capacitor EC2 starts to be charged at the moment, the voltage recovers 220V voltage in a short time because a variable frequency controller enters a chopped wave non-chopping part, at the moment, the first capacitor EC2 starts to discharge, the first diode D13 is reversely cut off, under the combined action of the first capacitor EC2 and the first diode D13, the voltage can be kept at the voltage value of the high-voltage pulse, at the moment, the controller connected through VDC monitors abnormal high-voltage pulse, and timely responses are sent out, for example, the circuit is powered off, and the like, so that the circuit and the variable frequency controller are protected.
On the other hand, as shown in fig. 2, the present invention further provides a frequency conversion control system for a motor, which includes an ac power supply, a frequency conversion controller, and the frequency conversion controller protection circuit as described above, and is particularly suitable for a frequency conversion control system for a non-inductive brushless permanent magnet motor without a large electrolytic capacitor.
Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. A frequency conversion controller protection circuit is characterized by comprising a rectifying circuit and a voltage holding circuit, wherein the input end of the rectifying circuit is suitable for being connected with an alternating current power supply, a frequency conversion controller is suitable for being connected between the output end of the rectifying circuit and the voltage holding circuit, and when a voltage signal collected from the voltage holding circuit is larger than a preset threshold value, the voltage input of the frequency conversion controller is cut off.
2. The protection circuit of claim 1, wherein the voltage holding circuit comprises a diode and a first capacitor, wherein an anode of the diode is connected to the output end of the rectification circuit, a cathode of the diode is connected to an anode of the first capacitor, and a cathode of the first capacitor is grounded.
3. The protection circuit of claim 2, further comprising a buck filter circuit coupled to the voltage holding circuit to collect the voltage signal.
4. The protection circuit of claim 3, wherein the buck filter circuit comprises a plurality of buck resistors and a second capacitor, the plurality of buck resistors are connected in series, one end of each buck resistor is connected between the diode and the first capacitor, the other end of each buck resistor is connected to ground, the second capacitor is connected in parallel with at least one buck resistor, and the voltage signal is collected from the connection end of the second capacitor and the buck resistor.
5. The protection circuit of claim 1, further comprising a temperature-sensitive resistor disposed between the output of the rectification circuit and the voltage holding circuit.
6. The protection circuit of claim 1, wherein the rectifying circuit comprises a rectifying bridge and a filter capacitor, an input end of the rectifying bridge is adapted to be connected to the ac power source, and an output end of the rectifying bridge is connected to the voltage holding circuit through the filter capacitor.
7. The protection circuit of claim 6, wherein the rectifier circuit further comprises a fuse device, and the fuse device is disposed on a live line of the input end of the rectifier bridge.
8. The protection circuit of claim 2, further comprising a low voltage supply port disposed between the diode and the first capacitor.
9. The protection circuit of any one of claims 1 to 8, further comprising a controller for obtaining the voltage signal.
10. A variable frequency control system for an electric motor comprising an ac power source, a variable frequency controller and a variable frequency controller protection circuit according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121660734.4U CN215580353U (en) | 2021-07-21 | 2021-07-21 | Frequency conversion controller protection circuit and motor frequency conversion control system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121660734.4U CN215580353U (en) | 2021-07-21 | 2021-07-21 | Frequency conversion controller protection circuit and motor frequency conversion control system |
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| Publication Number | Publication Date |
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| CN215580353U true CN215580353U (en) | 2022-01-18 |
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| CN202121660734.4U Active CN215580353U (en) | 2021-07-21 | 2021-07-21 | Frequency conversion controller protection circuit and motor frequency conversion control system |
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| CN (1) | CN215580353U (en) |
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2021
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