• 看看真正的电力是什么
• 了解我们为什么需要功率分析以及如何进行功率分析
• 了解如何进行功率分析以及什么是功率分析仪。

## 什么是功率分析仪？

SIRIUS XHS功率分析仪具有4路高压和4路低压放大器，用于电流传感器连接

## 什么是电力

• 电压是迫使水通过管道的压力。 压力越高，水将流动得越快。 以伏特（V）为单位。
• 电流是水流入的可用体积。体积越大，水可以流入的越多。 单位为安培（A）。
• 电阻是管道内部体积的减少，从而限制了水的流动。 单位为欧姆（R或Ω）。

## 我们如何计算电功率？

$P(t) = I(t) \cdot V(t)$

$V = I \cdot R$

$P = V \cdot I$

$P = I^2 \cdot R$

$P = \frac{V^2} {R}$

$P=\frac{1}{T}\int_{t=0}^T u(t)\cdot i(t)\;dt$

• P 是瓦特（W），功率
• i i是电流，安培（A）
• u 是电压，伏特（V）
• T 是周期时间（以秒为单位）

1. 有功功率（P）
2. 无功功率（Q）
3. 视在功率（S）

## 为什么我们要测量功率？

• 进行研发以提高产品和服务的性能
• 提高能源效率
• 减少成本和时间消耗
• 符合国家和国际标准确保产品和操作员的安全

## 功率分析仪做什么？

LED测试功率测量设置的示意图，其中使用来自Dewesoft的功率模块测量的AC和DC电压和电流波形

Dewesoft功率分析仪  不仅是世界上最小的功率分析仪，而且还是功能最强大的分析仪。 灵活的硬件平台与强大的软件功能相结合，为任何类型的电气测量提供了独特的测试可能性。 Dewesoft功率分析仪可以计算100多个功率参数，例如P，Q，S，PF，cos phi等。

• 原始数据记录功能
• 示波器
• FFT分析
• 谐波
• 等等

Dewesoft功率分析仪在单个设备中结合了多种仪器和功能-功率分析仪，FFT分析仪，原始数据记录仪，示波器，谐波分析仪，温度记录仪，振动记录仪等。

Dewesoft R8功率分析仪可配备多达64个高速模拟输入（每通道16位和5 MHz带宽时高达1 MS / s的速度），可在一个盒子中进行电压和电流测量。

Dewesoft R8DB功率分析仪可以配置64个通道，可以选择以适合多合一测量设备的测量应用

Dewesoft提供了范围广泛的电流传感器和电流传感器，可满足任何电流测量范围和精度要求

DewesoftX功率分析软件的典型三相三角形测量屏幕

## SIRIUS XHS-下一代功率分析仪

SIRIUS XHS功率分析仪 是SIRIUS系列的最新版本。 它是一个高速数据采集系统，能够以高达15 MS / s / ch的速度记录8个模拟输入，并具有高达5 MHz的带宽

SIRIUS XHS展示了四个HV放大器和四个LV放大器

• SIRIUS XHS HV高度隔离的CAT II 1000V高压模拟输入。 该放大器可直接测量20 V至2000 V峰值范围，带宽为5 MHz，精度为0.03％。 该放大器非常适合直接连接高压信号。 此放大器的连接器始终是绝缘的安全香蕉插孔（红色/黑色）。
• SIRIUS XHS LV：高度隔离的低压模拟输入。 该放大器可以测量0.05 V至100 V的范围，具有5 MHz的带宽，精度为0.03％，并且可以激励选定的传感器（需要DSUB9连接器进行传感器激励）。 该放大器非常适合直接连接低压信号和电流传感器。 该放大器的连接器可用于DSUB9或BNC。 请注意，DSUB9连接器还提供传感器激励以及用于智能传感器设置的TEDS。

• DSI-ACC 用于IEPE加速度计和麦克风
• DSI-CHG 用于电荷式加速度计
• DSI-RTD 用于RTD温度传感器
• DSI-TH 用于热电偶（J，K，T等）
• DSI-LVDT 用于LVDT位移/距离传感器

When any DSI model is connected to an LV channel, Dewesoft X data acquisition software automatically detects it (using TEDS sensor standard), and configures that channel for it, setting the input type, gain, range, and scaling to be appropriate. The user can make further settings, and save them into the on-board sensor database.

Noise floor, common-mode rejection, gain and offset drifts of both amplifiers at lower bandwidth are comparable to the standard DualCoreADC SIRIUS line of instruments.

These amplifiers are perfect for e-mobility measurements, where the highest precision such as power analysis is an absolute necessity.

## 内置FFT分析的功率分析仪

Conventional power analyzers use zero-point detection to determine the periodic time. This means that they evaluate when the voltage or current crosses that x-axis and use that value to calculate the periodic time.

Dewesoft on the other hand uses a special FFT (Fast Fourier Transform) algorithm to determine the periodic time (frequency).

Based on this predetermined period time, an FFT analysis of voltage and current can be done for a definable number of periods (typically 10, if the system’s base frequency is 50 Hz), and at a selectable sample rate. The FFT analysis yields an amplitude for the voltage, current, and the cos phi for each harmonic.

The Dewesoft power module has a built-in FFT analyzer in addition to the other visual display types

## 多相功率分析仪

In the Dewesoft X power module, there are several predefined system configurations available to choose from. The most common ones are:

• Direct current,
• 1-phase
• 2-phase - is used, e.g. with special types of motors
• 3-phase star
• 3-phase delta
• Aron and V configuration is basically star and delta configurations but measuring only two currents instead of three. This is normally done as a space-saving or cost reduction measure.

Special configurations such as 6-, 7-, 9- or 12 phase motor measurement can be done with multiple single-phase or 3-phase systems and adding up the power values in the Math library. This means that power can be measured at multiple points completely synchronous.

In the math library, the power modules can be further refined, for example, the efficiency can be calculated automatically. This is also very helpful when measuring multi-phase motors (6 to 12 phases).

The Dewesoft power module can be configured for 1, 2, and 3-phase systems. These can be combined to create 6, 7. 9 or even 12-phase systems

Engineers can simply select one or more of the systems that they are measuring from this list:

• 1-Phase
• 2-Phase
• 3-Phase star
• 3-Phase delta
• 3-phase Aron
• 3-phase V
• 3-phase 2-meters

In addition, a wide range of other choices is available, including the line frequency, output units, frequency source (the channel to be evaluated to determine the exact frequency), phase, and more.

Due to the modular design of Dewesoft measurement devices, the user is never limited to only measuring power values. Dewesoft DAQ systems can connect to virtually every sensor in the world, which means that the engineer can also measure temperature, force, vibration, sound, GPS, video, speed, RPM, torque, etc.

The Dewesoft power analyzer wiring schematic for testing inverter and electric motors

Engineers performing tests on electric or hybrid vehicles may also want to measure the speed of the car, the battery temperature, CAN bus data, GPS position, and even plot its exact location on a test track.

Instead of using two, three, or even more different measuring instruments, Dewesoft offers all measurements to be recorded simultaneously within a single instrument. This brings several key advantages:

• No need to merge the data together manually after the measurement.
• Data is completely synchronized down to a single sample.
• All the data can be viewed on one screen and written to one data file.
• Configuring and using only one DAQ system and software saves a lot of test preparation time.

Dewesoft Power Analyzer Explained Live at the Battery Show Expo

## 传感器数据库提高了电流和电压测量精度

It should be noted that every amplifier, current, and voltage transducer has some kind of inaccuracy or non-linearity. However, with Dewesoft power analyzers, these errors can be measured ahead of time and entered into an XML sensor database. Dewesoft X software applies correction factors in real-time, resulting in more accurate readings and results.

The Dewesoft analog sensor database

The built-in sensor database also eliminates errors caused by manual data entry mistakes. Selecting a transducer from the list rather than entering the parameters manually not only saves time, but it prevents typographical errors which can lead to wrong scaling or gain selections.

Inside the sensor database, scaling can be set up using y=mx+b formulas, look-up tables, polynomials, and even transfer curves. This only has to be done once for most sensors. Engineers can add, edit and delete sensors, and update their calibration information at any time, including CAL due dates, etc.

The sensor database’s units are based on and derived from the seven international SI unit “defining constants”:

• Length - meter (m)
• Time - second (s)
• Amount of substance - mole (mole)
• Electric current - ampere (A)
• Temperature - kelvin (K)
• Luminous intensity - candela (cd)
• Mass - kilogram (kg)

So while they are metric at their core, such as m/s2, for example, the user is free to select G or g, in this case. Therefore the output engineering units can be comfortable for all users worldwide.

Dewesoft software also includes sensor databases for counter/encoder/RPM sensors.

## 用Dewesoft测量电流

Current measurement is usually divided into two major groups:

• Direct
• Indirect

Direct” - is when the conductor must be disconnected and a sensor is connected in series with the circuit. This method works without any additional circuits.

The most common direct current measurement device is a shunt resistor, which is then connected in series with the circuit. A shunt resistor has a very low resistance which has been very accurately determined by the manufacturer. A shunt resistor works on the principle that when the current flows through this resistor, there will be a very small voltage drop that we can measure and convert to current using ohm’s law.

Typical shunt current measurement hook-up

We can measure this drop and apply Ohm’s law to calculate the current.

Graphical representation of Ohm’s Law

In addition, the accuracy of the resistor is an important factor, since this directly affects the accuracy of the measurement itself.

Dewesoft DSIi-10A Current Shunt

Dewesoft offers several compact size current shunts, each designed with a different burden resistor inside, intended to measure different current ranges. These shunts have been engineered to have the least possible effect on the circuit itself.

DSI adapters can be plugged into virtually all Dewesoft data acquisition devices. The isolated analog inputs of Dewesoft amplifiers is a crucial factor in ensuring accurate measurements, since the shunt is connected directly to the circuit being measured, and isolation between the circuit and the measuring system is always important. Isolated inputs mean that you can place your shunt on the low-side or high-side of the circuit, and not worry about a ground loop or common-mode measuring errors.

Considering Ohm’s law again and the interlocking nature of voltage, current, and resistance, it is absolutely clear that a DAQ system must be able to make a very accurate voltage measurement and resistance measurement in order to make an accurate current measurement.

Indirect” - is when the current sensor does not make contact with the circuit directly. Instead, it measures the magnetic field that is induced when current flows through a conductor and then converts it to a current reading (Electric charges produce electric fields).

The advantage of indirect current measurement is galvanic isolation of the sensor from the conductor and the fact that the circuit itself does not have to be disturbed or disconnected. It also allows very high currents to be measured.

Dewesoft supports nearly all of the current transducers available on the market today. Some of the current transducers can be powered directly from the measurement device and some current transducers require an external power supply, as the amount of excitation power that they need cannot be delivered by the measurement device.

Dewesoft has a solution for this: the SIRIUS PWR-MCTS2 is a power supply unit for powering these current transducers directly from Dewesoft instruments without any third party external power supply devices. The SIRIUS PWR-MCTS2 is offered in a compatible SIRIUS or SIRIUS XHS modular chassis or directly into a SIRIUS-based rack chassis such as R2DB, R3, R4, or R8 data acquisition system.

SIRIUS R8 with multiple measurement slices including rack compatible SIRIUS-PWR-MCTS2 as well as a modular chassis SIRIUS-PWR- MCTS2 and a SIRIUS 4xHV 4XLV

## SIRIUS XHS-PWR用于测试混合动力和电动汽车

Another innovation is the SIRIUS XHS-PWR, a new version of the classic SIRIUS DAQ system dedicated to testing hybrid and electric vehicles. It features a patented DC-CT current transducer technology that allows very precise current measurements, even in the most demanding applications, such as very high current peaks as well as leakage current testing.

The SIRIUS XHS-PWR with integrated DC-CT current transducer

This new instrument is perfect for e-mobility measurements, where the highest precision such as power analysis is an absolute necessity. The current transducer uses patented DC-CT® technology based on the Platiše Flux Sensor. It offers ranges of 100A, 500A, and 1000A, packed into a very small chassis, 1 MHz bandwidth, immunity to external magnetic fields, low offsets, and excellent linearity.

Typical in-vehicle power test, showing additional inputs like CAN bus, video camera, and real-time GPS position superimposed over a map

The amplifiers can also measure voltage 2000V peak (CAT II 1000V) with up to 5 MHz bandwidth

The SIRIUS XHS-PWR

This instrument has two inputs:

These inputs connect directly to the power line of the vehicle, for the ultimate in e-mobility testing convenience, bandwidth, and accuracy. It offers an IP65 degree of protection which allows the usage in harsh environments and during rough drives.

### Comparison table of DC-CT current transducer versus other current sensor types:

Type Isolated Range Bandwidth Linearity Accuracy Temp. drift Consumption
DC-CT DC/AC Yes High High Excellent Very High Very Low Medium
Fluxgate DC/AC Yes High High Excellent Excellent Low High
Hall DC/AC Yes High Medium Medium Medium High Low-Med
Shunt DC/AC No Medium Medium Good High Medium High
Rogowsky AC Yes High High Good Medium Low Low
CT AC Yes High Medium Medium Medium Low Low

## 兼容的电流互感器

Below is a table that gives a short overview of the current transducers that are available and which characteristics these transducers possess, as well as for which applications they are best suited.

### Overview of current transducers and their application areas

Properties Applications
Type AC DC Range Accuracy Bandwidth Pros Cons Power Analyzer E-mobility Grid monitoring
Iron-core current clamps YES NO 5 kA 0,5 - 4 % 10 kHz Cheap Heavy
Inflexible
Low bandwidth
NO NO YES
Cheap Rogowsky Coil YES NO 10 kA 1 % 20 kHz Rugged
Flexible
Linear
No magnetic influence
No DC measurement
High position errors
NO NO YES
Good Rogowsky Coil YES NO 50 kA 0,3 % Up to 20 MHz Rugged
Flexible
Linear
No magnetic influence
No DC measurement
High position errors
PARTLY PARTLY YES
Hall-compensated AC/DC current clamp YES YES 300 A 1,5 % 100 kHz AC/DC measurement
High accuracy
High bandwidth
Clamp can open
Low measurement range YES YES YES
Fluxgate AC/DC current clamp YES YES 700 A 0,3 % 500 kHz AC/DC measurement
High accuracy
High bandwidth
Clamp can open
Needs external power supply YES YES YES
Zero-flux current transducer YES YES 2000 A 0,002 % Up to 300 kHz AC/DC measurement
High accuracy
High bandwidth
Low phase error
Low offset
Can not be opened
Needs external power supply
YES YES YES

Dewesoft designs and produces world-renowned measurement and data acquisition equipment for a wide range of industries and applications. A focus since the early 2000s has been power analysis and power quality analysis.

Little did we know back then that automobiles would be turning electric at such a rapid pace as they are today. And that’s just one application where portable, high-performance power analyzers and power quality analyzer measuring instruments are essential.