阅读说明：本技术 逆变器保护装置 (Inverter protection device ) 是由 梁镇圭 于 2019-07-11 设计创作，主要内容包括：本发明公开一种逆变器保护装置。所述逆变器保护装置根据从并联连接的安全继电器的第一开关和第二开关接收的电压信号,来确定是否阻断向逆变器的逆变器部提供的脉冲宽度调制(PWM)控制信号,包括：第一电源开关,通过从所述第一开关施加的第一电压信号成为接通状态；第二电源开关,通过从所述第二开关施加的第二电压信号成为接通状态；以及缓冲器部,根据所述第一电源开关和所述第二电源开关的输出功率而被控制其通断,并将PWM控制信号提供到逆变器部。(The invention discloses an inverter protection device. The inverter protection device determines whether to block a Pulse Width Modulation (PWM) control signal provided to an inverter part of an inverter according to voltage signals received from first and second switches of safety relays connected in parallel, including: a first power switch that is turned on by a first voltage signal applied from the first switch; a second power switch that is turned on by a second voltage signal applied from the second switch; and a buffer unit which is controlled to be turned on and off according to output power of the first power switch and the second power switch, and supplies a PWM control signal to the inverter unit.)

1. An inverter protection apparatus that determines whether to block a Pulse Width Modulation (PWM) control signal supplied to an inverter part of an inverter according to voltage signals received from first and second switches of safety relays connected in parallel, comprising:

a first power switch that is turned on by a first voltage signal applied from the first switch;

a second power switch that is turned on by a second voltage signal applied from the second switch; and

and a buffer part which is controlled to be on and off according to the output power of the first power switch and the second power switch and supplies a PWM control signal to the inverter part.

2. The inverter protection device according to claim 1,

the buffer section includes: a first buffer receiving power in a conductive state of the first power switch; and a second buffer receiving power in an on state of the second power switch, the first buffer and the second buffer being connected in series between a pwm control part outputting the pwm control signal and the inverter.

3. The inverter protection device according to claim 2,

further included are a first insulating portion that is located between the first switch and the first power switch and insulates a first voltage signal, and a second insulating portion that is located between the second switch and the second power switch and insulates a second voltage signal.

4. The inverter protection device according to claim 2,

the first power switch is replaced with a first insulation type power switch for insulating a first voltage signal, and the second power switch is replaced with a second insulation type power switch for insulating a second voltage signal.

5. The inverter protection device according to claim 2,

the power supply further comprises a first filter part and a second filter part, wherein the first filter part is located between the first power switch and the first buffer, the second filter part is located between the second power switch and the second buffer, and the first filter part and the second filter part remove the switch ripple.

6. The inverter protection device according to claim 4,

further comprising a first filter section and a second filter section, the first filter section being located between the first insulation type power switch and the first buffer, the second filter section being located between the second insulation type power switch and the second buffer, and the first filter section and the second filter section removing a switching ripple.

Technical Field

The present invention relates to an inverter protection device, and more particularly, to an inverter protection device capable of improving the stability of a circuit.

Background

In recent years, electric devices such as motors have been widely used. At the same time, the possibility of serious accidents due to abnormal operation of the electrical equipment is also increasing. Therefore, it is desirable to reduce the risk of accidents as much as possible.

In order to bring these risks within the permitted limits, international standards are established. IEC61508 is a standard for electrical equipment, and IEC61800-5-2 is a standard established for driving equipment such as motors.

When a safety signal is input, the inverter should not deliver power to the motor as defined in IEC 61800-5-2.

Fig. 1 is a block diagram showing a conventional inverter protection device.

Referring to fig. 1, a conventional inverter protection device 130 is provided inside an inverter 100 and can supply +24V power to a safety relay 140 disposed outside the inverter 100.

The safety relay 140 is composed of a first switch 141 and a second switch 142 arranged in parallel, and is in a closed state in a normal operation state.

When any one of the first switch 141 and the second switch 142 of the safety relay 140 opens the contact by various safety actions of the inverter 100, the protection device 130 performs a protection action to protect the inverter 100.

The safety action of the inverter 100 may be performed by a host control part (not shown) or may be performed by a mechanical contact action.

The inverter 100 includes: an inverter unit 110 including a plurality of switching elements, for outputting a dc voltage as an ac voltage and supplying the ac voltage to the motor; a PWM control unit 150 that outputs a Pulse Width Modulation (PWM) control signal for controlling the switching elements of the inverter unit 110 to output an ac voltage in accordance with a command voltage; and a buffer unit 120 for supplying the PWM control signal to the inverter unit 110.

The buffer part 120 may apply the PWM control signal supplied from the PWM control part 150 to the gate of the switching element of the inverter part 110. For example, the power can be turned on or off by 5V power. That is, when 5V power is applied, the PWM control signal is applied to the inverter unit 110. When the power of 5V is not applied, the state is turned off, so that the PWM control signal cannot be applied to the inverter part 110.

The inverter protection device 130 includes a first insulating portion 131, a second insulating portion 132, a first power switch 133, a second power switch 134, and a monitoring portion 135.

The first insulating portion 131 may insulate a voltage signal applied from the first switch 141. The second insulating portion 132 may insulate the voltage signal applied from the second switch 142. Here, the insulation means to prevent direct power movement between the input side and the output side and block abnormal voltage for safety. The first insulating portion 131 and the second insulating portion 132 each include an optical coupler, and are connected to a power supply on the secondary side.

The first and second power switches 133 and 134 are turned on or off by using the secondary-side voltages of the first insulating portion 131 and the second insulating portion 132 as control voltages, respectively.

The first and second power switches 133 and 134 of the power switch section 136 are connected in series, respectively, and may be connected in series with a power line of 5V, respectively. That is, when the control voltage is applied from the first and second switches 141 and 142, the first and second power switches 133 and 134 are turned on, and power of 5V is applied to the buffer section 120.

The buffer unit 120 is turned on when 5V power is supplied, and applies the PMW control signal applied from the PWM control unit 150 to the inverter unit 110.

If the buffer section 120 is not supplied with 5V power, it switches to the off state. The PWM control signal applied from PWM control unit 150 is not applied to inverter unit 110.

The monitoring unit 135 determines whether or not the voltage signals of the node a, the node B, and the node C are normal. The node a is located between the first insulating portion 131 and the first power switch 133. Node B is located between the second insulating part 132 and the second power switch 134, and node C is located on the power line between the second power switch 134 and the buffer part 120.

As described above, in the conventional inverter protection circuit, when the first power switch 133 and the second power switch 134 are connected in series with each other and at least one of the first power switch 133 and the second power switch 134 is in an off state, the power supply to the snubber unit 120 is blocked.

As described above, the secondary side voltages of the first insulating portion 131 and the second insulating portion 132, which are the photocouplers, are used as the control voltages of the first power switch 133 and the second power switch 134.

Although the entire circuit constituting the conventional inverter protection device uses the same ground potential, since the first power switch 133 and the second power switch 134 are connected in series, the first power switch 133 may be in a state where the ground potential is unstable.

For example, in a state where the second power switch 134 is closed, the ground potential of the first power switch 133 is the same as the ground potential of the buffer section 120 applied by the second power switch 134, and thus stable operation is possible. However, in the state where the second power supply switch 134 is off, the ground potential of the first power supply switch 133 is in a floating state, and there is a problem that the normal operation may not be possible even if the secondary side voltage of the first insulating portion 131 is applied to the first power supply switch 133 to be 5V.

Disclosure of Invention

Problems to be solved by the invention

The invention provides an inverter protection device capable of preventing a floating state of a ground potential and improving the stability of a circuit.

Technical scheme for solving problems

In order to solve the above-described technical problem, in an inverter protection device of the present invention, which determines whether to block a Pulse Width Modulation (PWM) control signal supplied to an inverter part of an inverter according to voltage signals received from first and second switches of safety relays connected in parallel, the inverter protection device includes: a first power switch that is turned on by a first voltage signal applied from the first switch; a second power switch that is turned on by a second voltage signal applied from the second switch; and a buffer unit which is controlled to be turned on and off according to output power of the first power switch and the second power switch, and supplies a PWM control signal to the inverter unit.

In an embodiment of the present invention, the buffer section includes: a first buffer receiving power in a conductive state of the first power switch; and a second buffer receiving power in a conductive state of the second power switch, the first buffer and the second buffer may be connected in series between a pulse width modulation control part outputting the pulse width modulation control signal and the inverter.

In the embodiment of the present invention, the method may further include: a first insulating portion that is located between the first switch and the first power switch and insulates a first voltage signal, and a second insulating portion that is located between the second switch and the second power switch and insulates a second voltage signal.

In an embodiment of the present invention, the first power switch may be replaced with a first insulation type power switch that insulates the first voltage signal, and the second power switch may be replaced with a second insulation type power switch that insulates the second voltage signal.

In the embodiment of the present invention, the method may further include: a first filter section and a second filter section, the first filter section being located between the first power switch and the first buffer, the second filter section being located between the second power switch and the second buffer, and the first filter section and the second filter section removing a switching ripple.

In the embodiment of the present invention, the method may further include: a first filter section and a second filter section, the first filter section being located between the first insulation type power switch and the first buffer, the second filter section being located between the second insulation type power switch and the second buffer, and the first filter section and the second filter section removing a switching ripple.

Effects of the invention

The present invention has an effect of preventing the ground potential of the power switch from floating and improving the stability by independently configuring the power switch and connecting in series a plurality of buffers which are turned on by the power transmitted through the power switch.

Drawings

Fig. 1 is a configuration diagram of a conventional inverter protection device.

Fig. 2 is a block diagram showing the configuration of an inverter protection device according to a preferred embodiment of the present invention.

Fig. 3 and 4 are operation explanatory diagrams of the present invention, respectively.

Fig. 5 and 6 are block diagrams showing the configuration of an inverter protection device according to another embodiment of the present invention.

Description of reference numerals

1: inverter 2: electric motor

10: inverter unit 20: buffer part

21: first buffer 22: second buffer

30: protection device 31: first insulating part

32: second insulating portion 33: first power switch

34: second power switch 35: monitoring section

36: power switch unit 40: safety relay

41: first switch 42: second switch

50: PWM control unit

Detailed Description

In order that the structure and effects of the present invention can be fully understood, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be implemented in various forms and may be variously changed. However, the description of the present embodiments is intended to provide a complete disclosure of the present invention and to fully disclose the scope of the present invention to those of ordinary skill in the art to which the present invention pertains. In the drawings, the size of constituent elements is exaggerated and the scale of constituent elements may be exaggerated or reduced for convenience of explanation.

The terms "first", "second", and the like may be used to describe various constituent elements, but these constituent elements should not be limited to the above terms. The above terms may be used only to distinguish one constituent element from another constituent element. For example, a "first constituent element" may be named a "second constituent element", and similarly, a "second constituent element" may also be named a "first constituent element", without departing from the scope of the present invention. Furthermore, unless the context clearly dictates otherwise, expressions in the singular include expressions in the plural. Terms used in the embodiments of the present invention may be construed as meanings well known to those skilled in the art, unless otherwise defined.

Hereinafter, an inverter protection device according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 2 is a configuration diagram of an inverter protection device according to a preferred embodiment of the present invention.

Referring to fig. 2, the inverter protection device 30 of the present invention is provided inside the inverter 1, and can supply +24V power to the safety relay 40 disposed outside the inverter 1. However, this is merely exemplary, and a voltage having a magnitude different from 24V may be provided according to a rated voltage of the inverter 1 or the like, or a power supply may be provided from outside the inverter 1.

The safety relay 40 may include a first switch 41 and a second switch 42 configured in parallel. The closed state of the safety relay 40 is a normal operation state.

The safety relay 40 is a relay manufactured according to the safety standard of the relay in order to enhance safety of various mechanical devices, and its configuration is well known in the art, and thus detailed description thereof is omitted.

The protection device 30 of the present invention is used to perform a protection action to protect the inverter 1 when any one of the first and second switches 41, 42 of the safety relay 40 opens the contact by various safety actions of the inverter 1.

The safety action of the inverter 1 may be performed by a host control part (not shown), or may be performed by a mechanical contact action.

In an embodiment of the present invention, the inverter 1 may include: an inverter unit 10 including a plurality of switching elements, outputting a dc voltage as an ac voltage and supplying the ac voltage to a motor; a PWM control unit 50 that outputs a Pulse Width Modulation (PWM) control signal for controlling the switching elements of the inverter unit 10 to output an ac voltage in accordance with a command voltage; and a buffer unit 20 for supplying the PWM control signal to the inverter unit 10.

The switching elements of the inverter unit 10 may be, for example, IGBTs, but the present invention is not limited thereto, and various power semiconductor switching elements may be used.

The buffer part 20 may apply the PWM control signal supplied from the PWM control part 50 to the gate of the switching element of the inverter part 10. For example, the power of 5V can be turned on or off. That is, the PWM control signal is applied to the inverter part 10 in an on state when the power of 5V is applied, and the PWM control signal is not applied to the inverter part 10 in an off state when the power of 5V is not applied.

The buffer section 20 may be a gate block.

In an embodiment of the present invention, the inverter protection device 30 may include a first insulating portion 31, a second insulating portion 32, a first power switch 33, a second power switch 34, and a monitoring portion 35.

The first insulating portion 31 may insulate a voltage signal applied from the first switch 41. The second insulating portion 32 may insulate the voltage signal applied from the second switch 42.

Here, the insulation means to prevent direct power movement between the input side and the output side and block abnormal voltage for safety.

Each of the first insulating portion 31 and the second insulating portion 32 may be an optical coupler.

The first and second power switches 33, 34 may be, for example, metal-oxide-semiconductor field-effect transistors (MOSFETs), but the present invention is not limited thereto, and various power semiconductor switches may be used.

The first and second power switches 33 and 34 are turned on by the secondary-side voltages of the first insulating portion 31 and the second insulating portion 32. At this time, the secondary side voltages of the first insulating portion 31 and the second insulating portion 32 may be voltage signals higher than the threshold voltages (threshold voltages) of the first and second power switches 33, 34.

It is assumed that the first and second power switches 33, 34 switch the 5V power and selectively control the buffer section 20, respectively. The first power switch 33 and the second power switch 34 are provided in an independent state without a mutual coupling relationship. In addition, the buffer portion 20 includes: a first buffer 21 selectively receiving a voltage of 5V through a first power switch 33 to be turned on and off; and a second buffer 22 selectively receiving the 5V voltage through a second power switch 34 to be turned on and off.

The first buffer 21 and the second buffer 22 are connected in series between the PWM control section 50 and the inverter section 10.

Accordingly, in a state where both the first and second power switches 33 and 34 are closed, the 5V power voltage is supplied to each of the first and second buffers 21 and 22, so that the PWM control signal of the PWM control part 50 can be supplied to the inverter part 10.

When at least one of the first and second power switches 33 and 34 is in an off state, the PWM control signal of the PWM control part 50 may be blocked from being supplied to the inverter part 10.

The monitoring unit 35 determines whether or not the voltage signals at the nodes a, B, C, and D are operating in a normal state. Node a is located between the first insulating portion 31 and the first power switch 33. Node B is located between the second insulating part 32 and the second power switch 34. Node C is located on the power line between the first power switch 33 and the first buffer 21. Node D is located on the power line between the second power switch 34 and the second buffer 22.

The monitoring unit 35 may include, for example, an AND gate as a logic gate, AND may supply a monitoring signal indicating a circuit failure to the outside when any one of the voltage signals at the A, B, C, D node has a Failure (FAULT). For example, the monitoring signal may be provided to an external user terminal through a communication line.

In addition, when a Human Machine Interface (HMI) or a Programmable Logic Controller (PLC) is provided in the inverter 1, a monitoring signal may be provided to the HMI or the PLC.

In an embodiment of the present invention, the monitoring unit 35 may determine whether the voltage signal is normally applied to each node, i.e., whether the voltage signal operates in a normal state. Rather than determining the failure of individual elements.

That is, the monitoring unit 35 may reflect the failure state of the protection device 30 inside the inverter 1 and output the failure state.

In an embodiment of the present invention, it is exemplified that the monitoring section 35 outputs the normal state of each node of the protection device 30 as a monitoring signal through an AND gate, but the present invention is not limited thereto. For example, a plurality of monitoring units may be provided to output monitoring signals indicating the normal states of the respective nodes, and the HMI, PLC, or external user terminal may confirm the states of the nodes corresponding to the monitoring signals.

As described above, according to an embodiment of the present invention, the state of the circuit can be easily grasped by the monitoring section 35.

Hereinafter, the operation of the protection device 30 according to the present invention will be described in detail with reference to fig. 3 and 4.

Fig. 3 is a diagram for explaining an example of an operation when voltage signals from the safety relay 40 are respectively supplied to the protection device 30, and fig. 4 is a diagram for explaining an example of an operation when the contact of the second switch 42 of the safety relay 40 is opened according to a safety operation.

Referring to fig. 3, the voltage signal applied from the first switch 41 of the safety relay 40 is insulated by the first insulating portion 31, and the secondary-side voltage of the first insulating portion 31 is applied to the first power switch 33, so that the first power switch 33 is in an on state. In addition, the voltage signal applied from the second switch 42 of the safety relay 40 is insulated by the second insulating portion 32, and the secondary-side voltage of the second insulating portion 32 is applied to the second power switch 34, so that the second power switch 34 can be brought into an on state.

When the first power switch 33 and the second power switch 34 are closed, the first and second buffers 21 and 22 connected in series are both turned on when the first power switch 33 and the second power switch 34 receive 5V power.

When the first and second buffers 21 and 22 connected in series to each other of the buffer unit 20 are turned on, the PWM control signal generated by the PWM control unit 50 is applied to the gate of the switching element of the inverter unit 10 through the buffer unit 20, whereby an ac signal can be output to the motor 2.

Referring to fig. 4, when the second switch 42 of the safety relay 40 is turned off by the safety operation, no voltage signal is applied to the gate of the second power switch 34, and thus the second power switch 34 is turned off (turned off).

As described above, in the related art, when the second power supply switch 34 is in the off state, the ground potential of the first power supply switch 33 floats.

However, according to the present invention, it is possible to prevent the first power switch 33 and the second power switch 34 from being brought into an unstable floating state by having separate ground potentials.

That is, the voltage signal applied from the first switch 41 of the safety relay 40 is insulated by the first insulating portion 31 and applied to the first power switch 33, so that the first power switch 33 can be stably brought into an on state.

Since the second power switch 34 is in an off state, it is possible to block the 5V power from being supplied to the second buffer 22, thereby blocking the PWM control signal of the PWM control part 50 from being supplied to the inverter part 10.

Fig. 5 is a block diagram showing the configuration of an inverter protection device according to another embodiment of the present invention.

Referring to fig. 5, another configuration is the same as the inverter protection device described with reference to fig. 2, but it does not use the first insulating portion 31 and the second insulating portion 32, and the first power switch 33 and the second power switch 34 may be replaced with a first insulating type power switch 37 and a second insulating type power switch 38 that include an insulating function.

The first and second insulation type power switches 37 and 38 may be one module including a transistor whose gate is provided with an optocoupler.

The first and second insulation type power switches 37 and 38 are turned on or off according to voltage signals supplied through the first and second switches 41 and 42 of the safety relay 40, respectively, thereby controlling the supply of 5V power to the first and second buffers 21 and 22.

Specifically, as in the above-described embodiment, the ground potential of the first insulated power supply switch 37 can be prevented from floating regardless of the operating state of the second insulated power supply switch 38, and stable operation can be achieved.

Fig. 6 is a block diagram showing the configuration of an inverter protection device according to another embodiment of the present invention.

Referring to fig. 6, the other configuration is the same as the example of the inverter protection device described with reference to fig. 2, but the inverter protection device may further include a first filter unit 61 and a second filter unit 62, the first filter unit 61 being located between the first snubber 21 and the first power switch 33, and the second filter unit 62 being located between the second snubber 22 and the second power switch 34.

The first and second filter sections 61 and 62 remove switching ripples of the first and second power switches 33 and 34, respectively, to enable stable supply of 5V power.

In addition, the first filter section 61 and the second filter section 62 can function to compensate for a voltage drop caused by the diode components of the first power switch 33 and the second power switch 34.

While embodiments in accordance with the present invention have been described above, these are merely exemplary, and those skilled in the art can embody various embodiments within various modifications and equivalent scope. Therefore, the true technical scope of the present invention should be determined by the appended claims.

Industrial applicability

The present invention is industrially applicable as a technique for preventing a floating state of an inverter by using a natural law.