阅读说明：本技术 一种在线检测自举电容容值的方法 (Method for detecting capacitance value of bootstrap capacitor on line ) 是由 周清泉 刘金周 于 2021-08-09 设计创作，主要内容包括：本发明公开了一种在线检测自举电容容值的方法,该方法包括：以固定时间T对自举电容充入电荷量Q的电量,通过持续的开关对该电荷量Q进行消耗,统计总开关次数为X-(1)；再以固定时间T对所述自举电容再次充入电荷量Q的电量,再通过持续的开关对该电荷量Q进行消耗,统计总开关次数为X-(2),通过公式C-(2)＝C-(1)*X-(1)/X-(2)计算得到该自举电容的实时容值C-(2),其中,C-(1)为自举电容固定容值。本发明的有益效果在于：通过判断自举电容容值的下降比例,从而可以提前报警或提醒客户,保障功率器件能够正常运行,减少停机和停产,经济效益明显。(The invention discloses a method for detecting capacitance value of a bootstrap capacitor on line, which comprises the following steps: charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q in a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X 1 (ii) a Charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q again within a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X 2 By the formula C 2 ＝C 1 *X 1 /X 2 Calculating to obtain the real-time capacitance value C of the bootstrap capacitor 2 Wherein, C 1 The capacitance value is fixed for the bootstrap capacitor. The invention has the beneficial effects that: by judging the reduction proportion of the capacitance value of the bootstrap capacitor, the alarm or the reminding of a client can be carried out in advance, the normal operation of a power device can be ensured, the shutdown and the production halt can be reduced, and the economic benefit is obvious.)

1. A method for detecting capacitance value of a bootstrap capacitor on line is characterized by comprising the following steps: charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q in a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₁(ii) a Charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q again within a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₂By the formula C₂＝C₁*X₁/X₂Calculating to obtain the real-time capacitance value C of the bootstrap capacitor₂Wherein, C₁The capacitance value is fixed for the bootstrap capacitor.

Technical Field

The invention relates to the technical field of capacitance detection, in particular to a method for detecting a capacitance value of a bootstrap capacitor on line.

Background

The bootstrap circuit is widely applied to an electric power driving device, and the principle of the bootstrap circuit is as shown in fig. 1, when an N-side IGBT is turned on, a power supply VD charges a bootstrap capacitor through a current-limiting resistor and a bootstrap diode, so as to provide a driving power supply for the P-side IGBT.

Therefore, the function of the bootstrap capacitor is very important, the selection of the capacitance value of the capacitor is very critical, if the capacitance value is too small, enough charges cannot be stored to complete the switching-on of the upper bridge power tube, and if the capacitance value is too large, the voltage value required by the switching-on cannot be charged, so that the upper bridge power tube cannot be switched on. In view of this, the bootstrap capacitor cannot be connected in parallel for a plurality of times like a power supply type capacitor to increase the reliability redundancy of the system, and meanwhile, the bootstrap capacitor generally needs to be installed at a position close to the power device, which generates a large amount of heat when the power device works, and thus, the capacitance value reduction of the bootstrap capacitor is aggravated. Once the capacitance value of the bootstrap capacitor is reduced, the whole power device can be caused to fail.

Disclosure of Invention

The invention discloses a method for detecting capacitance value of a bootstrap capacitor on line, which can effectively solve the technical problems involved in the background technology.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for detecting capacitance value of a bootstrap capacitor on line is characterized by comprising the following steps: charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q in a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₁(ii) a Charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q again within a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₂By the formula C₂＝C₁*X₁/X₂Calculating to obtain the real-time capacitance value C of the bootstrap capacitor₂Wherein, C₁The capacitance value is fixed for the bootstrap capacitor.

The invention has the following beneficial effects: by judging the reduction proportion of the capacitance value of the bootstrap capacitor, the alarm or the reminding of a client can be carried out in advance, the normal operation of a power device can be ensured, the shutdown and the production halt can be reduced, and the economic benefit is obvious.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a circuit diagram of a prior art bootstrap circuit;

fig. 2 is a circuit diagram of a three-phase circuit according to embodiment 1 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides a method for detecting capacitance value of a bootstrap capacitor on line, which comprises the following steps: charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q in a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₁(ii) a Charging the bootstrap capacitor with the electric quantity of the electric charge quantity Q again within a fixed time T, consuming the electric charge quantity Q through a continuous switch, and counting the total switching times to be X₂By the formula C₂＝C₁*X₁/X₂Calculating to obtain the real-time capacitance value C of the bootstrap capacitor₂Wherein, C₁The capacitance value is fixed for the bootstrap capacitor. According to the obtained real-time capacitance value C of the bootstrap capacitor₂The reduction proportion of the capacitance value of the bootstrap capacitor can be judged, so that an alarm can be given out in advance or a client can be reminded, the normal operation of a power device can be guaranteed, the shutdown and the production halt can be reduced, and the economic benefit is obvious.

The following describes in detail a method for online detecting a capacitance value of a bootstrap capacitor according to the present invention in specific embodiment 1.

Example 1

The method for detecting the capacitance value of the bootstrap capacitor on line can be used for power switch circuits of single-phase full bridges, two-phase full bridges, three-phase full bridges and multi-phase full bridges, and a three-phase circuit is taken as an example.

As shown in fig. 2, T1, T3, and T5 are power transistors of a three-phase upper bridge, and each of the three power transistors has a bootstrap circuit including a resistor, a bootstrap capacitor, and a bootstrap diode. T2, T4 and T6 are power tubes of a three-phase lower bridge. Now, the process of detecting the bootstrap capacitance of the T1 bootstrap loop is exemplified as follows: 1. turn off T3, T4, T5, T6; 2. turning on T2 for a fixed time S1, thereby charging a certain charge Q1 to the bootstrap capacitor of the bootstrap circuit of T1; 3. closing T2, opening T4, performing a pulse sequence switch with the continuous on-time of S2 and the off-time of S3 on a power tube T1, detecting the value of the motor current as I, when the motor current is detected to be not lower than a certain fixed threshold value, considering that the charge amount of the bootstrap capacitor can complete the minimum charge requirement of normal switching of the power device, accumulating the total times X of switching when the motor current is not lower than the certain fixed threshold value, and stopping accumulating the total times X of switching when the charge amount of the bootstrap capacitor is completely consumed when the motor current is lower than the certain fixed value.

The invention has the following beneficial effects: by judging the reduction proportion of the capacitance value of the bootstrap capacitor, the alarm or the reminding of a client can be carried out in advance, the normal operation of a power device can be ensured, the shutdown and the production halt can be reduced, and the economic benefit is obvious.

Having thus disclosed the invention by reference to certain of its aspects and embodiments, the invention is not limited to the details shown and described herein, and it is to be understood that the same is capable of numerous modifications and that other modifications may readily occur to those skilled in the art, without departing from the general concept defined by the appended claims and their equivalents.