TWI711262B - Inverter device and method for selectively outputting current according to output voltage value - Google Patents

Abstract

An inverter device includes an inverter module, an output filter, a bypass circuit, a output voltage 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 output voltage value comprising the steps of: first, uses a output voltage detector to detect a output voltage value between the output filter and the load; and then uses the control module to compare whether the output voltage value is greater than a output voltage limit value; finally, when the output voltage value is greater than the output voltage 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 and selection based on output voltage value Method of selective output current

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 output voltage 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, because the pulse voltage is transmitted on the cable, if the impedance of the cable does not match the impedance of the load, reflection will occur at the load end, and the result of the reflection will cause the incident wave and the reflected wave to superimpose, thereby forming a higher voltage. The maximum amplitude can reach 2 of the DC bus voltage It is approximately equivalent to 3 times the input voltage of the inverter. Therefore, when an excessively high peak voltage is applied to the coil of the motor stator, the coil is likely to cause premature failure of the motor due to frequent overvoltage shocks, and even cause the coil The insulation layer is damaged and causes other hazards.

In conclusion, in order to avoid output voltage damage to equipment or personal injury, the output filter is usually directly connected to the drive device to filter the current output by the drive device, thereby preventing the pulse voltage from being reflected on the load end. High voltage. Although this method can effectively avoid the formation of high voltage, it will cause power loss due to excessive filtering.

In view of the fact that in the prior art, the use of an external output filter to avoid the formation of high voltage will cause power loss; therefore, the main purpose of the present invention is to provide a frequency converter device and selectively output current according to the output voltage value. The method can effectively avoid the formation of high voltage, and will not cause power loss due to excessive filtering.

In order to solve the problems of the prior art, the necessary technical means adopted by the present invention is to provide a frequency converter device, which includes a frequency converter module, an output filter, a bypass circuit, an output voltage detection circuit and a control module.

The frequency converter module 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 or variable voltage AC power.

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 output voltage detection circuit includes a detection contact and an output voltage detector. The detection contact is electrically connected to the output contact and the load. The output voltage 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 an output voltage value, and send an output voltage signal accordingly.

The control module is electrically connected to the inverter module, the conduction switch and the output voltage detector, and is used to send a disconnection signal to the conduction switch according to the output voltage 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 filtering the power frequency alternating current provided by the mains power supply. The frequency converter is electrically connected to the input filter and the output filter for the filtered The power frequency alternating current of the wave is converted 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 output voltage limit value, and the comparator is used to compare the output voltage value with the output voltage Limit value, and send the disconnection signal when the output voltage value is greater than the output voltage limit value. Preferably, the output voltage limit value is 1.5 to 2 times the voltage of the power frequency alternating current.

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 output voltage value, which is applied to the above-mentioned inverter device, which selectively outputs according to the output voltage value. The current method includes the following steps: First, step (a) is to use the output voltage detector to detect the output voltage value between the output filter and the load, and send the output voltage signal to The control module; then, step (b) is to use the control module to receive the output voltage signal, and compare whether the output voltage value is greater than an output voltage limit value; finally, step (c) is when the output voltage value When the output voltage is greater than the limit value of the output voltage, the control module sends the disconnection signal to the conduction switch to drive the conduction switch from the preset conduction state to the disconnection state, so that the inverter module provides the The variable frequency alternating current is filtered by the output filter and then supplied to the load.

One of the subsidiary technologies derived from the above necessary technical means In the technical method, before step (a), a step (a0) is further included, using the inverter module to receive the power frequency AC power provided by the mains power supply, and converting the power frequency AC power into the variable frequency AC power.

As mentioned above, the present invention mainly presets the conduction switch to be in the conduction state, and uses the output voltage detector to detect whether the variable frequency AC power delivered to the load through the bypass circuit is too high due to voltage reflection, and then determines the inverter Whether the variable frequency AC power output by the module needs to be controlled by the output filter, effectively avoiding 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

1‧‧‧Inverter Module

11‧‧‧Input filter

12‧‧‧Inverter

2‧‧‧Output filter

3‧‧‧Bypass circuit

31‧‧‧Input contact

32‧‧‧Output contact

33‧‧‧On switch

4‧‧‧Output voltage detection circuit

41‧‧‧Detection contact

42‧‧‧Output voltage detector

5‧‧‧Control Module

51‧‧‧Comparator

511‧‧‧Output voltage 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‧‧‧Output voltage signal

S2‧‧‧Open circuit signal

The first figure is a system block diagram of the inverter device 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 output voltage 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 the inverter device provided by the preferred embodiment of the present invention. As shown in the figure, an inverter device 100 includes an inverter module 1, an output filter 2, a bypass circuit 3, an output voltage 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 frequency conversion 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, the frequency conversion The converter 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, when the frequency conversion of the present invention When the inverter device 100 is turned on, the inverter module 1 will first filter and convert the power frequency AC power provided by the mains power supply 200 into variable frequency AC power. Then, because the conduction switch 33 is preset to conduct, the inverter module 1 The supplied variable frequency AC power will be first delivered to the load 300 through the bypass circuit 3. In addition, in this embodiment, the conduction switch 33 is a relay.

The output voltage detection circuit 4 includes a detection contact 41 and And an output voltage 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 output voltage 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 output voltage detector 42 can detect an output voltage 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 output voltage is detected When the output voltage value is generated, an output voltage signal S1 is issued according to the output voltage value.

The control module 5 is electrically connected to the inverter module 1, the conduction switch 33 and the output voltage detector 42, and has a comparator 51, and the comparator 51 has an output voltage limit value 511 built in, and the output voltage limit value 511 is 1.5 to 1.5 times the voltage of the power frequency alternating current; among them, the comparator 51 is used to compare the output voltage value with the output voltage limit value 511, and when the output voltage value is greater than the output voltage limit value 511, it sends a disconnection signal S2 to The conduction switch 33 switches the conduction switch 33 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 detector 62 is electrically connected to the mains voltage detection contact 61 and the control module 5 for detecting Measure the commercial power supply 200 input frequency AC power of inverter module 1 And send the detected voltage value to the 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 output voltage value provided by the preferred embodiment of the present invention. As shown in the figure, on the basis of the inverter device 100 described above, the present invention provides a method for selectively outputting current according to the output voltage value. The first step S11 is to use the inverter module 1 to receive the information provided by the mains power supply 200. Power frequency AC power, and convert power frequency AC power into variable frequency AC power. Next, step S12 is to use the output voltage detector 42 to detect the output voltage value between the output filter 2 and the load 300, and send the output voltage signal S1 to the control module 5 according to the output voltage value. Then, step S13 is to use the control module 5 to receive the output voltage signal S1 and compare whether the output voltage value is greater than an output voltage limit value 511. Finally, when the output voltage value is greater than the output voltage limit value 511, it will proceed to step S14, but if the output voltage value is less than the output voltage limit value 511, it will end directly; where, in step S14, the control module 5 sends a circuit breaker signal S2 is connected to the conduction switch 33 to drive the conduction switch 33 from the preset conduction state to the disconnection state.

In summary, since the inverter device of the present invention presets the conduction switch 33 to be in the conductive state, the commercial power supply 200 provides the commercial power supply 200 after the inverter module 1 outputs the variable frequency AC power. The resistance of the pass circuit 3 is much smaller than the resistance of the output filter 2, so the variable frequency AC output from the inverter module 1 will first be transmitted to the load 300 through the bypass circuit 3; at this time, because the detection contact 41 is set in the bypass circuit Between the output contact 32 of 3 and the load 300, the output voltage detector 42 electrically connected to the detection contact 41 can detect whether the voltage value of the variable-frequency AC power delivered to the load 300 through the bypass circuit 3 is too high , And when the output voltage detector 42 detects the output voltage, the output voltage signal S1 is sent to the control module 5, so that the comparator 51 of the control module 5 compares the output voltage value with the output voltage limit value 511.

When the detected output voltage value is greater than the output voltage 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 alternating current is filtered by the output filter 2 and then sent to the load 300. Since the output filter 2 can filter out the reflected wave, it can avoid the formation of high voltage and effectively protect the insulation layer of the coil of the load 300. . In addition, since the inverter device of the present invention presets the conduction switch 33 to be in the conduction state, when the detected output voltage value is not greater than the output voltage limit value 511, it can be used without filtering through the output filter 2. Provide variable frequency alternating current to the load, effectively avoiding energy loss caused by excessive filtering.

Compared with the prior art inverter devices, most of them filter the reflected wave through an external output filter to avoid The high voltage causes the output power to be reduced due to the filtering of the output filter even if the variable frequency AC power that does not originally form a high voltage; in contrast, the inverter device of the present invention is compared with the output current based on the output voltage value. The method can effectively control whether the variable frequency AC output from the inverter module needs to pass through the output filter through the output voltage detection, so as to effectively avoid unnecessary loss caused by excessive 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

1‧‧‧Inverter Module

11‧‧‧Input filter

12‧‧‧Inverter

2‧‧‧Output filter

3‧‧‧Bypass circuit

31‧‧‧Input contact

32‧‧‧Output contact

33‧‧‧On switch

4‧‧‧Output voltage detection circuit

41‧‧‧Detection contact

42‧‧‧Output voltage detector

5‧‧‧Control Module

51‧‧‧Comparator

511‧‧‧Output voltage 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‧‧‧Output voltage signal

S2‧‧‧Open circuit signal

Claims (8)

A frequency converter device, 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; An output voltage detection circuit, including: A detection contact is electrically connected to the output contact and the load; and An output voltage detector is electrically connected to the detection contact to detect the variable frequency AC power delivered to the load through the bypass circuit to generate an output voltage value, and send out an output voltage signal accordingly ;as well as A control module is electrically connected to the inverter module and the conduction switch And the output voltage detector for sending a disconnection signal to the conduction switch according to the output voltage signal, so that the conduction switch is switched from the conduction state to a disconnection state, so that the inverter module provides the The variable frequency alternating current is filtered by the output filter and then supplied to the load. The inverter device 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 frequency converter device described in item 2 of the scope of patent application, wherein the frequency converter is a matrix frequency converter. For the inverter device described in item 1 of the scope of patent application, the control module further includes a comparator, the comparator has a built-in output voltage limit value, and the comparator is used to compare the output voltage value with the Output voltage limit value, and send out the circuit break signal when the output voltage value is greater than the output voltage limit value. For the inverter device described in item 4 of the scope of patent application, the output voltage limit value is 1.5 to 2 times the voltage of the power frequency alternating current. In the inverter device described in item 1 of the scope of patent application, the conduction switch is a relay. A method of selectively outputting current according to the output voltage value is to use the inverter device as described in the scope of the patent application to selectively output the variable frequency alternating current to the load, and the output current is selectively output according to the output voltage value The method includes the following steps: (a) Use the output voltage detector to detect the output voltage value between the output filter and the load, and send the output voltage signal to the control module according to the output voltage value; (b) Use the control module to receive the output voltage signal, and compare whether the output voltage value is greater than an output voltage limit value; and (c) When the output voltage value is greater than the output voltage limit value, the control module Send the disconnection signal to the conduction switch to drive the conduction switch from the preset conduction state to the disconnection 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. As described in item 7 of the scope of patent application, the method of selectively outputting current based on the output voltage value, wherein, before step (a), it further includes a step (a0), using the inverter module to receive the mains power supply The power frequency AC power should be converted into the variable frequency AC power.

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