阅读说明：本技术 用于使在具有一个或多个被切换的电抗性负载的电源中的逆变器的峰值功率需求最小化的设备 (Apparatus for minimizing peak power requirements of an inverter in a power supply having one or more switched reactive loads ) 是由 简.卡罗.特冼拿.萨帕塔 尼尔·乔治·斯图尔特 于 2018-04-26 设计创作，主要内容包括：提供了一种用于使具有一个或多个被切换的电抗性负载的电源中的逆变器上的峰值功率需求最小化的设备,该设备包括与逆变器并联连接的AC半导体旁路开关和旁路控制。旁路控制包括滤波器,用于从被切换的电抗性负载中选择具有特定频率的负载电流信号；信号处理器,用于将所选择的负载电流信号采样并转换到频域以识别所选择的负载电流信号的频率分量；幅度检测器,用于检测所选择的负载电流信号的已识别的频率分量的峰值电流幅度；以及一个旁路驱动器。(An apparatus for minimizing peak power requirements on an inverter in a power supply having one or more switched reactive loads is provided, the apparatus comprising an AC semiconductor bypass switch connected in parallel with the inverter and a bypass control. The bypass control includes a filter for selecting a load current signal having a particular frequency from the switched reactive loads; a signal processor for sampling and converting the selected load current signal to the frequency domain to identify frequency components of the selected load current signal; an amplitude detector for detecting a peak current amplitude of the identified frequency component of the selected load current signal; and a bypass driver.)

1. An apparatus for minimizing peak power requirements of an inverter in a power source having one or more switched reactive loads, the apparatus comprising:

an AC semiconductor bypass switch connected in parallel with the inverter; and

a bypass control, comprising:

one or more filters for selecting one or more load current signals having a particular associated frequency from the switched reactive loads;

a signal processor for sampling and converting the selected load current signal to a frequency domain to identify frequency components of the selected load current signal;

an amplitude detector for detecting a peak current amplitude of the identified frequency component of the selected load current signal; and

a bypass driver for driving the AC semiconductor bypass switch, the bypass driver configured to divert transient load current away from the inverter for over-current protection or to act as an actively controlled current source to provide a transient load current of a desired magnitude.

2. The apparatus of claim 1, wherein the signal processor samples and converts the filtered and selected load current signal to a frequency domain using a fourier transform method.

3. The apparatus of claim 1 wherein said bypass control includes a high pass filter for filtering and selecting the high frequency transient load current signal.

4. The apparatus of claim 1 wherein said bypass control includes a low pass filter for filtering and selecting the low frequency transient load current signal.

5. The apparatus of claim 1, wherein the AC semiconductor bypass switch is operable normally in a saturation region of its V-I characteristic when the AC semiconductor bypass switch is configured to divert transient load current from the inverter for over-current protection.

6. The apparatus of claim 1 wherein when the AC semiconductor bypass switch is configured to act as an actively controlled current source, the AC semiconductor bypass switch operates normally in the active region of its VI characteristic such that the AC semiconductor bypass switch can provide a transient load current of a desired magnitude in response to a drive signal from the bypass driver.

7. The apparatus of claim 1, wherein the AC semiconductor bypass switch is configured to always bypass an amount of current to cause the inverter to act as a voltage regulated reference voltage.

8. The apparatus of claim 1, wherein the bypass control further comprises a digital or analog comparator for comparing the detected peak current amplitude of the identified frequency component of the selected load current signal with one or more reference values.

9. The apparatus of claim 8, wherein the bypass driver drives the AC semiconductor bypass switch to bypass the selected load current when any of the detected peak current amplitudes of the identified frequency components of the selected load current signal is above its respective reference value.

10. The apparatus of claim 1, wherein the AC semiconductor bypass switch comprises one or more reverse IGBTs, FETs, BJTs or unipolar devices in a rectifier bridge structure comprising IGBTs, FETs, BJTs.

11. The apparatus of claim 1, further comprising a semiconductor relay device and an electromechanical bypass device, both connected in parallel with the primary of the transformer or magnetic structure;

wherein the semiconductor relay device and the electromechanical bypass device are triggered and controlled by the bypass control to divert the transient load current from the inverter for over-current protection.

12. The apparatus of claim 1, further comprising a Current Transformer (CT) for measuring a load current waveform to be fed to the switched reactive load.

Technical Field

The present invention generally relates to an electronic AC-AC series voltage regulation topology that utilizes inverter power semiconductors to handle the total peak power to the load. In particular, the present invention relates to minimizing peak power requirements on an inverter in a power supply having one or more reactive loads that are switched.

Background

An AC voltage regulator is used to closely control and regulate the level of an AC voltage delivered to a load connected to the output of the AC voltage regulator despite AC voltage variations at the input of the AC voltage regulator. The electronic AC-AC series regulation structure may be any "direct" topology such that the inverter power semiconductors have to handle the total peak power of the load, or any "indirect" electronic AC-AC voltage regulation topology utilizing a low frequency transformer that handles only a part of the total output power (the low frequency transformer may be selected from those disclosed in international patent application No. PCT/B2017/055260, the disclosure of which is incorporated herein by reference). Typically, an AC voltage regulator will utilize inverter power semiconductors to handle the total peak power of the load. However, the limited power handling capabilities inherent in inverter power semiconductor devices may cause problems with electronic AC-AC series voltage regulation. It is well known that small power semiconductor dies have limited critical heat dissipation, and therefore, they can only handle current transients of limited peak amplitude caused by switched reactive loads. In particular, when the inverter power semiconductor devices are connected to switched reactive loads with high and very high instantaneous peak power currents, unnecessary and troublesome bypass operations may be triggered. Therefore, inverter power semiconductor devices must be designed and specified with greater power handling capability, even beyond a specified power, to handle high peak power transients, and generally use power semiconductor devices with greater than ideal required power to handle lower RMS or average load power.

Fig. 1 shows a generic electronic AC-AC series voltage regulator with a standard conventional bypass, typically including a semiconductor bypass switch, mechanical relay or contactor bypass, for protecting inverter power semiconductor devices subject to high peak currents, according to prior art examples. The semiconductor bypass switch may be a fast switching AC semiconductor device (e.g., a TRIAC or SCR) which may be inverted or have a rectifier bridge connected in parallel with the contacts of a slower mechanical relay or contactor. In this way, the conventional bypass may be used as a fast protection bypass with fast AC power semiconductors and slower mechanical relays or contactors. A current magnitude detector is used to detect transient peak current magnitudes from the load current sensor and a bypass driver is used to trigger a conventional bypass.

The switched load may comprise a resistive (R) load and a reactive load comprising capacitive (C) and/or inductive (L) elements. Fig. 5 shows the inverter current waveform after implementation of the apparatus shown in fig. 1. When reactive loads are switched to the inverter, transient high peaks in load current lasting only a few microseconds or milliseconds may cause very high (up to 115.1Amps) transient inverter current peaks exceeding the current protection level preset by the protection current magnitude detector, thereby unnecessarily triggering the conventional bypass. This may lead to disturbing bypass operations, leading to disturbing lighting flicker and even to destructive voltage fluctuations. Therefore, the power requirements of inverter power semiconductor devices are to handle not only the average or RMS power dissipated by the resistive load, but also the high amplitude transient current peaks caused by the reactive load. Therefore, in order to maintain a regulated output without triggering the bypass, the inverter power semiconductor devices are generally of a considerable size, even exceeding a prescribed size.

Disclosure of Invention

It is an object of the present invention to directly alleviate or eliminate the critical industry-inherent problems of limited peak power handling capability of inverter power semiconductor devices. According to one aspect of the invention, there is provided an apparatus for minimizing peak power demand on an inverter in a power supply having one or more switched reactive loads, the apparatus comprising an AC semiconductor bypass switch and a bypass control connected in parallel with the inverter. The bypass control includes: one or more filters for selecting one or more load current signals having a particular associated frequency from the switched reactive loads; and a signal processor for sampling and converting the selected load current signal to the frequency domain to identify frequency components of the selected load current signal; an amplitude detector for detecting a peak current amplitude of the identified frequency component of the selected load current signal; and a bypass driver for driving the AC semiconductor bypass switch, configured to divert transient load current from the inverter for over-current protection, or to act as an actively controlled current source to provide a transient load current of a desired magnitude.

Drawings

Embodiments of the invention are described in more detail below with reference to the accompanying drawings, in which

Fig. 1 depicts a general purpose electronic AC-AC series voltage regulator with standard conventional bypass according to a prior art example.

FIG. 2 depicts an apparatus for minimizing peak power demand on an inverter in a power supply having one or more switched reactive loads according to one embodiment of the present invention; wherein the AC semiconductor bypass switch is configured to divert transient load current from the inverter for over-current protection.

FIG. 3 depicts another apparatus for minimizing peak power demand on an inverter in a power supply having one or more switched reactive loads according to one embodiment of the present invention; wherein the AC semiconductor bypass switch is configured to act as an actively controlled current source to provide a transient load current of a desired magnitude.

FIG. 4 depicts another apparatus for minimizing peak power demand on an inverter in a power supply having one or more switched reactive loads according to one embodiment of the present invention;

fig. 5 shows the inverter current waveform after implementation of the apparatus shown in fig. 1.

Fig. 6 shows the inverter current waveform after implementing the apparatus shown in fig. 2.

Fig. 7 shows the inverter current waveform after implementation of the apparatus shown in fig. 3.

Detailed Description

In the following description, as a preferred example, there is presented a method, system and apparatus, etc. for minimizing peak power requirements of an inverter in a power supply having one or more switched reactive loads in an AC-AC series voltage regulation topology. It will be apparent to those skilled in the art that modifications, including additions and/or substitutions, may be made without departing from the scope and spirit of the invention. Specific details may be omitted in order to avoid obscuring the invention. This disclosure, however, is written to enable one skilled in the art to practice the teachings herein without undue experimentation.

Fig. 2 illustrates an apparatus for minimizing peak power demand on an inverter in a power supply having one or more switched reactive loads according to one embodiment of the present invention. The apparatus includes an AC semiconductor bypass switch connected in parallel with the inverter; and bypass control. The AC semiconductor bypass switch may be one of a reverse or fast switching AC semiconductor device (e.g., a triac or SCR) having a rectifier bridge connected in parallel with the contacts of a slower mechanical relay or contactor. The AC semiconductor bypass switch may comprise one or more reverse IGBTs, FETs, BJTs or unipolar devices incorporating IGBTs, FETs, BJT rectifier bridge structures as disclosed in PCT/IB2017/055260, the disclosure of which is incorporated herein by reference.

The bypass control may include one or more filters for selecting one or more load current signals having a particular associated frequency from the switched reactive loads. The filter may include a high pass filter for filtering and selecting high frequency transient load current signals and a low pass filter for filtering and selecting low frequency transient load current signals.

The bypass control may also include a signal processor for sampling and transforming the selected load current signal into the frequency domain to identify frequency components of the selected load current signal. Preferably, the signal processor may sample and transform the filtered and selected load current signal into the frequency domain using a fourier transform method.

The bypass control may further comprise an amplitude detector for detecting a peak current amplitude of the identified frequency component of the selected load current signal. The current magnitude detector will drive the bypass driver to trigger the conventional bypass when the detected transient peak current exceeds a preset protection current level.

The bypass control may also include a digital or analog comparator for comparing the detected peak current amplitude of the identified frequency component of the selected load current signal with one or more reference values to protect the inverter power semiconductors of the AC-AC series regulator.

The bypass control may further comprise a bypass driver for driving the AC semiconductor bypass switch to bypass the selected load current when any one of the detected peak current amplitudes of the identified frequency components of the selected load current signal is above its respective reference value. Preferably, the bypass driver may include a proportional-integral-derivative (PID) error amplifier for regulating the drive signal of the AC semiconductor bypass switch.

As shown in fig. 2, the AC semiconductor bypass switch may be configured to divert transient load current from the inverter for over-current protection, and preferably, the AC semiconductor bypass switch may functionally operate in a saturation region of its V-I characteristic such that the AC semiconductor bypass switch may provide a desired magnitude of transient load current in response to a drive signal from the bypass driver.

Alternatively, as shown in fig. 3, the AC semiconductor bypass switch may be configured to act as an actively controlled current source to provide a desired magnitude of transient load current, and preferably the AC semiconductor bypass switch is functionally operable in the region of its VI characteristic such that the AC semiconductor bypass switch can provide the desired magnitude of transient load current in response to a drive signal from the bypass driver.

Optionally, the AC semiconductor bypass switch may be configured to always bypass an amount of current to cause the inverter to act as a voltage regulated reference voltage.

In some embodiments, the apparatus may further comprise a semiconductor relay arrangement and an electromechanical bypass arrangement, both connected in parallel with the primary of the transformer or magnetic structure. The semiconductor relay device and the electromechanical bypass device are triggered and controlled by a bypass control to divert transient load current away from the inverter for over-current protection.

In some embodiments, the apparatus may further comprise a Current Transformer (CT) for measuring a load current waveform to be fed to the switched reactive load.

In one embodiment, as shown in fig. 4, the device may include a passive frequency selective bypass that acts as a filter for the passage of current. The filtered transient load current signal is removed from the inverter to provide over-current protection.

With the present invention, different instantaneous current peaks can be selectively bypassed since the load current signal can be selectively processed so that the AC-AC series voltage regulator can step and settle to average or RMS load power normally and simply without erroneously triggering the bypass.

Fig. 6 illustrates an improved inverter current waveform after implementation of the apparatus shown in fig. 2, wherein the AC semiconductor bypass switches are configured to divert transient load current away from the inverter for over-current protection. The amplitude of the transient inverter current peak is reduced to 25.6 amps.

Fig. 7 illustrates an improved inverter current waveform after implementation of the apparatus shown in fig. 3, wherein the AC semiconductor bypass switches are configured to act as actively controlled current sources to provide transient load currents of a desired magnitude.

Although the foregoing description and drawings describe only a single phase AC system, those skilled in the art may apply the inventive principles described herein to any multi-phase AC system, such as a three-phase electrical system, without departing from the scope and spirit of the present invention.

The embodiments disclosed herein may be implemented using general purpose or special purpose computing devices, computer processors, micro-controllers or electronic circuits including, but not limited to, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and other programmable logic devices configured or programmed according to the teachings of the present disclosure. Computer instructions or software code for execution in a general purpose or special purpose computing device, computer processor, or programmable logic device may be readily developed by those skilled in the software or electronics arts based on the teachings of the present disclosure.

The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations will be apparent to practitioners skilled in the art.

The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.