TWI717142B - Inverter device with output filter and method for selectively outputting current according to leakage current value - Google Patents

Abstract

An inverter device with a output filter includes an inverter module, an output filter, a bypass circuit, a leakage current detection circuit, and a control module. The inverter module is electrically connected to a mains supply. The output filter is electrically connected to the inverter module and a load. The bypass circuit is arranged in parallel with the output filter. Based on the inverter device, a method of selectively outputting current based on the leakage current value comprising the steps of: first, uses a leakage current detector to detect a leakage current value between the output filter and the load; and then uses the control module to compare whether the leakage current value is greater than a leakage current limit value; finally, when the leakage current value is greater than the leakage current limit value, the control module sends a disconnection signal to the switch to drive the switch to switch from a preset on-state to an off-state.

Description

Inverter device with built-in output filter and method for selectively outputting current according to leakage current value

The present invention relates to a frequency converter device and a method for selectively outputting current, in particular to a frequency converter device with a built-in output filter and a method for selectively outputting current according to the leakage current value.

Generally speaking, larger or more precise motors usually need to be controlled by a drive device such as a frequency converter to adjust the output power of the motor according to the needs of the user. However, since the power source of this type of motor is commercial power, When using a motor, in addition to installing a driver, it is usually necessary to install an input filter between the mains and the driving device to prevent the AC power provided by the mains from being damaged due to chaotic waveforms. In addition, the alternating current output through the drive device is often prone to leakage current due to excessive voltage or insulation damage, which may cause damage to the motor’s bearings or insulation and other equipment, and may even cause damage. Staff members were electrocuted and injured.

As mentioned above, in order to prevent leakage current from damaging equipment or causing personal injury, leakage current sensors are usually used to detect leakage current, but usually when leakage current sensors detect leakage current, they often trip directly and cause the motor Stop work, which may cause sudden stoppage or other dangers. In order to improve the problem of shutdown of the leakage current sensor when it detects the leakage current, the existing method is mainly to directly connect the output filter to the drive device to filter the current output by the drive device. However, this method can Effectively reduce the generation of leakage current, but it will cause continuous loss of current.

In view of the fact that in the prior art, the use of leakage current sensors to detect leakage current may cause sudden shutdown or other hazards, while the use of external output filters to reduce leakage current will cause continuous current loss; Therefore, the main purpose of the present invention is to provide an inverter device with a built-in output filter and a method for selectively outputting current according to the value of the leakage current, which can effectively avoid the generation of leakage current without excessive filtering. And cause the loss of current.

In order to solve the problems of the prior art, the necessary technical means adopted by the present invention is to provide an inverter device with a built-in output filter, which includes an inverter module, an output filter, a bypass circuit, and a leakage current detection circuit And a control module.

The inverter module is electrically connected to a mains power supply to convert a power frequency AC power provided by the mains power supply into a frequency or Variable frequency alternating current with variable voltage.

The output filter is electrically connected to the inverter module and a load for filtering the variable frequency alternating current provided by the inverter module and providing it to the load.

The bypass circuit includes an input contact, an output contact, and a conduction switch. The input contact is electrically connected to the inverter module and the output filter. The output contact is electrically connected to the output filter and the load. The conduction-on relationship is electrically connected to the input contact and the output contact to be set in parallel with the output filter, and the conduction switch is preset to a conduction state, so that the variable frequency AC power provided by the inverter module It is delivered to the load via the bypass circuit.

The leakage current detection circuit includes a detection contact and a leakage current detector. The detection contact is electrically connected to the output contact and the load. A leakage current detector is electrically connected to the detection contact to detect the variable-frequency alternating current delivered to the load through the bypass circuit to generate a leakage current value, and send a leakage current signal accordingly.

The control module is electrically connected to the inverter module, the conduction switch and the leakage current detector, and is used to send a disconnection signal to the conduction switch according to the leakage current signal, so that the conduction switch is in the conduction state Switch to a disconnected state, so that the variable frequency AC power provided by the inverter module is filtered by the output filter and then provided to the load.

In an auxiliary technical means derived from the above-mentioned necessary technical means, the inverter module includes an input filter and an inverter. The input filter is electrically connected to the mains power supply for the The power frequency AC power provided by the power source is filtered. The frequency converter is electrically connected to the input filter and the output filter for converting the filtered power frequency alternating current into the variable frequency alternating current. Preferably, the frequency converter is a matrix frequency converter.

In an auxiliary technical means derived from the above necessary technical means, the control module further includes a comparator with a built-in leakage current limit value, and the comparator is used to compare the leakage current value with the leakage current Limit value, and send the disconnection signal when the leakage current value is greater than the leakage current limit value. Preferably, the leakage current limit value is between 1 mA and 100 mA.

In one of the auxiliary technical means derived from the above necessary technical means, the on-switch is a relay.

In order to solve the problems of the prior art, another necessary technical method adopted by the present invention is to provide a method for selectively outputting current according to the leakage current value, which is applied to the above-mentioned inverter device with built-in output filter. The method of selectively outputting current by using leakage current value includes the following steps: First, step (a) is to use the leakage current detector to detect the leakage current value between the output filter and the load, and according to the leakage current value Send the leakage current signal to the control module; then, step (b) is to use the control module to receive the leakage current signal and compare whether the leakage current value is greater than a leakage current limit value; finally, step (c) ) Is when the leakage current value is greater than the leakage current limit value, the control module sends the disconnection signal to the conduction switch to drive the conduction switch to switch from the preset conduction state to the disconnection state, thereby enabling the frequency conversion The variable frequency alternating current provided by the converter module is filtered by the output filter and then supplied to the negative Load.

In one of the ancillary technical means derived from the above-mentioned necessary technical means, before step (a), it further includes a step (a0), using the inverter module to receive the power frequency AC power provided by the mains power supply, and the process The frequency alternating current is converted into the variable frequency alternating current.

As mentioned above, the present invention mainly presets the conduction switch to be in the conduction state, and uses the leakage current detector to detect whether the variable frequency AC power delivered to the load through the bypass circuit generates leakage current, and then determines the output of the inverter module Whether the variable frequency AC power needs to be controlled through the output filter, effectively avoiding the unnecessary loss caused by filtering.

The specific embodiments adopted in the present invention will be further explained by the following embodiments and drawings.

100‧‧‧Inverter device with built-in output filter

1‧‧‧Inverter Module

11‧‧‧Input filter

12‧‧‧Inverter

2‧‧‧Output filter

3‧‧‧Bypass circuit

31‧‧‧Input contact

32‧‧‧Output contact

33‧‧‧On switch

4‧‧‧Leakage current detection circuit

41‧‧‧Detection contact

42‧‧‧Leakage Current Detector

5‧‧‧Control Module

51‧‧‧Comparator

511‧‧‧Leakage current limit value

6‧‧‧Input voltage detection circuit

61‧‧‧Mains voltage detection contact

62‧‧‧Input voltage detector

7‧‧‧Current feedback circuit

71‧‧‧Output current detection contact

200‧‧‧Mains power supply

300‧‧‧Load

S1‧‧‧Leakage current signal

S2‧‧‧Open circuit signal

The first figure is a system block diagram of the inverter device with built-in output filter provided by the preferred embodiment of the present invention; and

The second figure is a flowchart showing the steps of the method for selectively outputting current according to the leakage current value provided by the preferred embodiment of the present invention.

Please refer to the first figure. The first figure shows a system block diagram of a frequency converter device with a built-in output filter provided by a preferred embodiment of the present invention. As shown in the figure, an inverter device 100 with built-in output filter includes an inverter module 1, an output filter 2, and a bypass circuit. 3. A leakage current detection circuit 4, a control module 5, an input voltage detection circuit 6 and a current feedback circuit 7.

The frequency converter module 1 includes an input filter 11 and a frequency converter 12. The input filter 11 is electrically connected to a mains power supply 200 for filtering a power frequency AC power provided by the mains power supply 200. The frequency converter 12 is electrically connected to the input filter 11 for converting the power frequency alternating current filtered by the input filter 11 into a variable frequency or variable voltage alternating current. In addition, in this embodiment, the frequency converter 12 is a matrix-type variable frequency converter in which nine SiC MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) electronic switches are arranged in a matrix, but it is not limited to this. In other embodiments In this case, the inverter module 1 can also be a combination of an existing rectifier and inverter.

The output filter 2 is electrically connected to the inverter 12 of the inverter module 1 and a load 300 for filtering the variable frequency AC power provided by the inverter module 1 and then providing it to the load 300.

The bypass circuit 3 includes an input contact 31, an output contact 32 and a conduction switch 33. The input contact 31 is electrically connected to the inverter module 1 and the output filter 2. The output contact 32 is electrically connected to the output filter 2 and the load 300. The conduction switch 33 is electrically connected to the input contact 31 and the output contact 32, so that the conduction switch 33 and the output filter 2 are arranged in parallel, and the conduction switch 33 is preset to a conduction state, thereby, the present invention When the inverter device 100 with output filter is turned on, the inverter module 1 will filter the commercial AC power provided by the mains power supply 200 and convert it into variable frequency AC power. Then, because the conduction switch 33 is preset to conduct, Therefore, the variable frequency AC power provided by inverter module 1 will pass through The bypass circuit 3 is delivered to the load 300. In addition, in this embodiment, the conduction switch 33 is a relay.

The leakage current detection circuit 4 includes a detection contact 41 and a leakage current detector 42. The detection contact 41 is electrically connected to the output contact 32 and the load 300; more specifically, the detection contact 41 is set on the circuit between the output filter 2 and the load 300, and is located between the output contact 32 and the load 300 between. The leakage current detector 42 is electrically connected to the detection contact 41; among them, since the detection contact 41 is located between the output contact 32 and the load 300, when the variable frequency AC power provided by the inverter module 1 passes through the bypass circuit 3 When it is delivered to the load 300, the leakage current detector 42 can detect a leakage current value generated by the variable frequency alternating current delivered to the load 300 through the bypass circuit 3 through the detection contact 41, and when the leakage current is detected When the leakage current value is generated, a leakage current signal S1 is issued according to the leakage current value.

The control module 5 is electrically connected to the inverter module 1, the conduction switch 33 and the leakage current detector 42, and has a comparator 51, and the comparator 51 has a leakage current limit value 511 built in, and the leakage current limit value 511 is between 1mA and 100mA; among them, the comparator 51 is used to compare the leakage current value with the leakage current limit value 511, and when the leakage current value is greater than the leakage current limit value 511, it sends a disconnection signal S2 to the conduction switch 33, The conduction switch 33 is switched from the preset conduction state to the disconnection state, so that the variable frequency AC power provided by the inverter module 1 is filtered by the output filter 2 and then provided to the load 300.

The input voltage detection circuit 6 includes a mains voltage detection contact 61 and an input voltage detector 62. The mains voltage detection contact 61 is set between the mains power supply 200 and the inverter module 1, and the input voltage detection The detector 62 is electrically connected to the mains voltage detection contact 61 and the control module 5, and is used to detect the voltage value of the commercial power supply 200 inputting the commercial frequency AC power of the inverter module 1 and the detected voltage value Send to control module 5.

The current feedback circuit 7 includes an output current detection contact 71. The output current detection contact 71 is set between the inverter 12 and the input contact 31 of the inverter module 1, and is electrically connected to the control module 5. In order to detect the current value of the variable frequency AC output from the inverter 12, and transmit the detected current value to the control module 5. In this embodiment, the control module 5 mainly controls the operating parameters of the inverter module 1 through information such as the voltage value of the power frequency alternating current and the current value of the variable frequency alternating current detected by the input voltage detector 62. This is the prior art, so it will not be described further.

Please continue to refer to the second figure. The second figure is a flow chart of the method for selectively outputting current according to the leakage current value provided by the preferred embodiment of the present invention. As shown in the figure, based on the inverter device 100 with built-in output filter, the present invention provides a method for selectively outputting current according to the leakage current value. First, step S11 is to use the inverter module 1 Receive the power frequency AC power provided by the mains power supply 200, and convert the power frequency AC power into variable frequency AC power. Next, in step S12, the leakage current detector 42 is used to detect the leakage current value between the output filter 2 and the load 300, and the leakage current signal S1 is sent to the control module 5 according to the leakage current value. Then, step S13 is to use the control module 5 to receive the leakage current signal S1 and compare whether the leakage current value is greater than a leakage current limit value 511. Finally, when the leakage current value is greater than the leakage current limit value 511, step S14 will continue, but if the leakage current value is less than the leakage current limit value 511, it will end directly; wherein, step S14 is the control module 5 sending a circuit breaker signal S2 To the conduction switch 33, to drive the conduction switch 33 to switch from the preset conduction state to the disconnection state.

To sum up, since the inverter device with built-in output filter of the present invention presets the conduction switch 33 to be in the conduction state, the commercial power supply 200 provides the power frequency AC power after the inverter module 1 frequency conversion. After outputting the variable frequency AC power, since the resistance of the bypass circuit 3 is much smaller than the resistance of the output filter 2, the variable frequency AC power output by the inverter module 1 will first be transmitted to the load 300 through the bypass circuit 3; at this time, due to the detection connection The point 41 is set between the output contact 32 of the bypass circuit 3 and the load 300, so the leakage current detector 42 electrically connected to the detection contact 41 can detect the frequency conversion delivered to the load 300 through the bypass circuit 3 Whether the alternating current generates leakage current, and when the leakage current detector 42 detects the leakage current, the leakage current signal S1 is sent to the control module 5 so that the comparator 51 of the control module 5 compares the leakage current value with the leakage current limit The value is 511.

When the detected leakage current value is greater than the leakage current limit value 511, the control module 5 sends a disconnection signal S2 to the conduction switch 33, so that the conduction switch 33 cuts off the bypass circuit 3, and the inverter module 1 The output variable frequency AC power is filtered by the output filter 2 and then sent to the load 300. Since the output filter 2 can suppress high-frequency harmonics, the leakage current can be reduced, and the insulation or bearings of the load 300 can be effectively protected. element. In addition, because the inverter device with built-in output filter of the present invention presets the conduction switch 33 to be in the conduction state, when the detected leakage current value is not greater than the leakage current limit value 511, it can be used without passing through The output filter 2 provides variable frequency alternating current to the load in the case of filtering, effectively avoiding the energy loss caused by filtering.

Compared with the prior art inverter devices, most of the high frequency harmonics are suppressed by an external output filter, thereby reducing leakage current generation. As a result, even the frequency conversion AC that does not originally generate leakage current will be filtered by the output filter. In contrast, the inverter device with built-in output filter and the method of selectively outputting current according to the leakage current value of the present invention can indeed effectively control the inverter through leakage current detection. Whether the variable frequency alternating current output by the module needs to pass through an output filter, so as to effectively avoid unnecessary losses caused by filtering.

Through the detailed description of the preferred embodiments above, it is hoped that the characteristics and spirit of the present invention can be described more clearly, and the scope of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, its purpose is to cover various changes and equivalent arrangements within the scope of the patent application for the present invention.

100‧‧‧Inverter device with built-in output filter

1‧‧‧Inverter Module

11‧‧‧Input filter

12‧‧‧Inverter

2‧‧‧Output filter

3‧‧‧Bypass circuit

31‧‧‧Input contact

32‧‧‧Output contact

33‧‧‧On switch

4‧‧‧Leakage current detection circuit

41‧‧‧Detection contact

42‧‧‧Leakage Current Detector

5‧‧‧Control Module

51‧‧‧Comparator

511‧‧‧Leakage current limit value

6‧‧‧Input voltage detection circuit

61‧‧‧Mains voltage detection contact

62‧‧‧Input voltage detector

7‧‧‧Current feedback circuit

71‧‧‧Output current detection contact

200‧‧‧Mains power supply

300‧‧‧Load

S1‧‧‧Leakage current signal

S2‧‧‧Open circuit signal

Claims (8)

An inverter device with built-in output filter, including: A frequency converter module, which is electrically connected to a mains power supply for converting a power frequency AC power provided by the mains power supply into a variable frequency AC power with variable frequency or voltage; An output filter is electrically connected to the inverter module and a load for filtering the variable frequency alternating current provided by the inverter module and providing it to the load; A bypass circuit, including: An input contact is electrically connected to the inverter module and the output filter; An output contact is electrically connected to the output filter and the load; and A conduction switch is electrically connected to the input contact and the output contact to be set in parallel with the output filter, and the conduction switch is preset to a conduction state, so that the inverter module provides the Variable frequency alternating current is delivered to the load via the bypass circuit; A leakage current detection circuit, including: A detection contact is electrically connected to the output contact and the load; and A leakage current detector is electrically connected to the detection contact to detect the variable frequency alternating current delivered to the load through the bypass circuit to generate a leakage current value, and send out a leakage current signal accordingly ;as well as A control module is electrically connected to the inverter module, the conduction switch and the leakage current detector, and is used to send a disconnection signal to the conduction switch according to the leakage current signal, so that the conduction switch is switched from the The on state is switched to an off state, so that the variable frequency alternating current provided by the inverter module is filtered by the output filter and then provided to the load. For example, the inverter device with built-in output filter described in item 1 of the scope of patent application, wherein the inverter module includes: An input filter is electrically connected to the mains power supply for filtering the power frequency AC power provided by the mains power supply; and A frequency converter is electrically connected to the input filter and the output filter for converting the filtered power frequency alternating current into the variable frequency alternating current. The inverter device with built-in output filter as described in item 2 of the scope of patent application, wherein the inverter is a matrix inverter. For example, the inverter device with built-in output filter described in the scope of patent application, wherein the control module further includes a comparator, the comparator has a built-in leakage current limit value, and the comparator is used for The leakage current value is compared with the leakage current limit value, and the open circuit signal is sent when the leakage current value is greater than the leakage current limit value. For the inverter device with built-in output filter described in item 4 of the scope of patent application, the leakage current limit value is between 1mA and 100mA. The inverter device with built-in output filter as described in item 1 of the scope of patent application, wherein the conduction switch is a relay. A method of selectively outputting current based on the value of leakage current is to use the inverter device with built-in output filter as described in item 1 of the scope of patent application to selectively output the variable-frequency alternating current to the load. The method of selectively outputting current by current value includes the following steps: (a) Use the leakage current detector to detect the leakage current value between the output filter and the load, and send the leakage current according to the leakage current value Signal to the control module; (b) use the control module to receive the leakage current signal, and compare whether the leakage current value is greater than a leakage current limit value; and (c) when the leakage current value is greater than the leakage current limit Value, the control module sends the disconnection signal to the conduction switch to drive the conduction switch to switch from the preset conduction state to the disconnection state, so that the variable frequency AC power provided by the inverter module receives the output The filter is filtered and supplied to the load. The method of selectively outputting current according to the leakage current value as described in item 7 of the scope of patent application, wherein, before step (a), it further includes In one step (a0), the frequency converter module is used to receive the power frequency AC power provided by the mains power supply, and the power frequency AC power is converted into the variable frequency AC power.

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