CN111313371A

CN111313371A - Bypass protection method for cascade power module

Info

Publication number: CN111313371A
Application number: CN202010141129.XA
Authority: CN
Inventors: 虞晓阳; 汪涛; 张茂强; 李乐乐; 李汉杰; 文继锋; 曹冬明
Original assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Current assignee: NR Electric Co Ltd; NR Engineering Co Ltd
Priority date: 2020-03-04
Filing date: 2020-03-04
Publication date: 2020-06-19

Abstract

The application provides a bypass protection method for a cascade power module. The power module at least comprises a bypass switch, a power semiconductor switch, a diode and a control board; the diode is connected in series with the bypass switch; the power semiconductor switch is connected in parallel with the bypass switch. The bypass protection method comprises the following steps: before the control panel controls the power module to complete the bypass, firstly, the control panel controls the power semiconductor switch to be switched on; and then the control board controls the bypass switch to complete the bypass. The method controls the reverse recovery speed of the diode by controlling the power semiconductor switch to be turned on, prevents the diode from running beyond a safe working area, and improves the safety and reliability of the bypass of the power module.

Description

Bypass protection method for cascade power module

Technical Field

The application relates to the field of power electronic equipment of a power system, in particular to a bypass protection method of a cascade power module.

Background

In the field of power systems, power electronic equipment generally applies a technical scheme of power devices connected in series or in cascade to form a power module due to high voltage level. In order to improve the operation reliability of power electronic equipment, particularly cascaded multi-level power equipment, a power module generally requires to be configured with a bypass function, and when the power module fails, the equipment can be maintained to continue to operate through the bypass power module, so that the expansion of faults and the economic loss are avoided.

The bypass function of the power module is generally realized by adopting a mechanical switch, in the switching-on process of the mechanical switch, the closing of a metal contact can cause the high voltage and current change rate of a power semiconductor device, and particularly when the original current flows through a diode, the bypass action of the bypass switch can cause the strong reverse recovery of the diode, so that the operation curve of the diode exceeds a safe working area, and the diode is damaged. At present, there is no relevant research and technology to mention the power module bypass protection aspect.

The application provides a cascade power module bypass protection method, aiming at a power module configured with a bypass switch, the influence of high voltage and current change rate caused by a bypass on the power module is eliminated, and the reliability of the bypass is improved.

Disclosure of Invention

The application provides a bypass protection method for a cascade power module aiming at the field of power electronic equipment of a power system and provided with a cascade power module with a bypass switch.

In the disclosed cascade power module bypass protection method, the power module comprises at least a bypass switch (K1), a power semiconductor switch (Q1), a diode (D1) and a control board; the diode (D1) is connected in series with a bypass switch (K1); the power semiconductor switch (Q1) is connected with a bypass switch (K1) in parallel or connected with a bypass switch (K1) through other switches in parallel; the method comprises the following steps:

the power module control board receives an upper computer instruction to send a control bypass command, or the power module control board detects a power module fault to send a bypass command;

the power module control board controls the power semiconductor switch Q1 to be switched on;

the power module control board controls the bypass switch K1 to complete the bypass.

In a further preferred embodiment of the present invention, the power semiconductor switch Q1 is an IGCT, BIGT, IGBT or MOSFET, and the control board turns off the power semiconductor switch Q1 after at least a time delay t elapses after controlling the power semiconductor switch Q1 to turn on.

As a further preferable aspect of the present invention, the delay time t is a closing control and operation delay time of the bypass switch K1.

As a further preferable aspect of the present invention, the power semiconductor switch Q1 is a thyristor, and the power semiconductor switch Q1 turns off in response to its current being lower than the holding current.

In a further preferred embodiment of the present invention, the diode (D1) is a parasitic diode of a separate device or a power semiconductor device.

In a further preferred embodiment of the present invention, the bypass switch (K1) is an electrical mechanical switch or an explosive mechanical switch.

According to the invention, the power semiconductor switch connected with the bypass switch in parallel is firstly switched on, the reverse recovery speed of the diode is controlled, and then the bypass switch is controlled to be switched on, so that the damage of the power module caused by the strong reverse recovery of the diode is avoided, and the safety and reliability of the bypass of the power module are improved.

Technical scheme

The application provides a cascade power module bypass protection method, which has the following advantages:

(1) the reverse recovery speed of the series diode can be controlled when the bypass switch is switched on, and the reverse recovery reliability of the diode is improved;

(2) according to the application, the time delay is reasonably set, the power module caused by possible bouncing of the metal contact of the bypass mechanical switch is prevented from bearing the electrical stress, and the safety and reliability of the bypass of the power module are improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram illustrating essential components of a cascaded power module provided in the present application;

fig. 2 is a schematic flowchart of a bypass protection method for a cascade power module according to the present application, which corresponds to fig. 1;

fig. 3 is a circuit diagram of a cascaded power module according to an embodiment of the present application.

Fig. 4 is a schematic flowchart illustrating a bypass protection method for a cascade power module according to the embodiment of fig. 3;

fig. 5 is a circuit diagram of a cascaded power module according to another embodiment of the present application;

fig. 6 is a schematic flowchart of a bypass protection method for a cascade power module according to the embodiment of fig. 5;

fig. 7 is a power module circuit to which a protection method for a cascaded power module according to the present application is applied.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, specific embodiments of the technical solutions of the present application will be described in more detail and clearly in the following with reference to the accompanying drawings and the embodiments. However, the specific embodiments and examples described below are for illustrative purposes only and are not limiting of the present application. It is intended that the present disclosure includes only some embodiments and not all embodiments, and that other embodiments may be devised by those skilled in the art with various modifications as fall within the scope of the appended claims.

The method provided by the application is a bypass protection method for the cascade power module.

Fig. 1 is a schematic diagram illustrating essential components of a cascade power module provided by the present application, including a bypass switch K1, a power semiconductor switch Q1, a diode D1, and a control board.

The bypass switch K1 is connected in series with the diode D1, the power semiconductor switch Q1 is connected in parallel with two ends of the bypass switch K1, and the control board can control the power semiconductor switch Q1 and the bypass switch K1.

Fig. 2 is a schematic flowchart of a cascade power module bypass protection method provided by the present application corresponding to fig. 1. In step S110, when the cascade power module fails, a bypass is required or the upper computer controls to send a bypass instruction; in step S120, the control board controls the power semiconductor switch Q1 to be turned on; in step S130, the control board controls the bypass switch K1 to be turned on, thereby completing the power module bypass operation.

Fig. 3 is a circuit diagram of a cascaded power module according to an embodiment of the present application. The circuit is a half-bridge circuit, the IGBT1 is connected with the IGBT2 in series, the bypass switch K1 is connected with two ends of the IGBT2 in parallel, and the C1 is a direct-current capacitor.

Fig. 4 is a schematic flowchart illustrating a bypass protection method for a cascade power module according to the embodiment of fig. 3; in step S110, when the cascade power module fails, a bypass is required or the upper computer controls to send a bypass instruction; in step S120, the control board controls the IGBT1 to turn off and the IGBT2 to turn on; in step S130, the control board controls the bypass switch K1 to be turned on; in step S140, after at least a delay t, the bypass switch K1 is turned on, and the control board controls the IGBT2 to turn off, thereby completing the power module bypass operation.

Fig. 5 is a circuit diagram of a cascaded power module according to another embodiment of the present application; the circuit is a half-bridge circuit, the IGBT1 and the IGBT2 are connected in series, the bypass switch K1 is connected in parallel at two ends of the IGBT2, the thyristor SCR1 is connected in parallel at two ends of the bypass switch K1, and C1 is a direct-current capacitor.

Fig. 6 is a schematic flowchart of a bypass protection method for a cascade power module according to the embodiment of fig. 5; in step S110, when the cascade power module fails, a bypass is required or the upper computer controls to send a bypass instruction; in step S120, the control board controls the IGBT1 to turn off and the SCR1 to turn on; in step S130, the control board controls the bypass switch K1 to be turned on; in step S140, the thyristor SCR1 current is turned off less than the holding current, completing the power module bypass operation.

It should be noted that the above-mentioned embodiments described with reference to the drawings are only intended to illustrate the present application and not to limit the scope of the present application, and those skilled in the art should understand that modifications or equivalent substitutions made on the present application without departing from the spirit and scope of the present application should be included in the scope of the present application. Furthermore, unless the context indicates otherwise, words that appear in the singular include the plural and vice versa. Additionally, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

Claims

1. A cascaded power module bypass protection method, characterized in that the power module comprises at least a bypass switch (K1), a power semiconductor switch (Q1), a diode (D1) and a control board; the diode (D1) is connected in series with a bypass switch (K1); the power semiconductor switch (Q1) is connected with a bypass switch (K1) in parallel or connected with a bypass switch (K1) through other switches in parallel; the method comprises the following steps:

2. The cascade power module bypass protection method of claim 1, wherein: the power semiconductor switch Q1 is an IGCT, a BIGT, an IGBT or an MOSFET, and the control panel controls the power semiconductor switch Q1 to be switched on and then switches off the power semiconductor switch Q1 after at least a delay of t time.

3. A method of cascade power module bypass protection as claimed in claim 2, characterized by: the delay t is the closing control and action delay time of the bypass switch K1.

4. The cascade power module bypass protection method of claim 1, wherein: the power semiconductor switch Q1 is a thyristor, and the power semiconductor switch Q1 turns off in response to its current being below the holding current.

5. The cascade power module bypass protection method of claim 1, wherein: the diode (D1) is a parasitic diode of a stand-alone device or a power semiconductor device.

6. The cascade power module bypass protection method of claim 1, wherein: the bypass switch (K1) is an electrical mechanical switch or an explosive mechanical switch.