Designing efficient magnetic components starts with understanding the material itself. Datasheets are useful, but when engineers need to evaluate ferrites, powder cores, nanocrystalline alloys, amorphous metals, silicon steel, or transformer laminations under realistic AC excitation, they need measured data rather than assumptions. An IWATSU B-H Analyzer is built for exactly that purpose: measuring the AC magnetic properties of soft magnetic materials and soft magnetic parts, including B-H curves, core loss, relative permeability, inductance, and complex permeability.

What a B-H Analyzer actually measures

A B-H analyzer reconstructs the hysteresis curve of a magnetic material by generating a magnetic excitation field and measuring the resulting magnetic response. In simple terms, it shows the relationship between magnetic field strength H and magnetic flux density B. That closed loop is not just a visual aid. It contains the information engineers care about most: saturation behavior, remanence, coercivity, permeability, and the energy loss associated with magnetic cycling.

This matters because magnetic materials are not ideal. They do not respond instantaneously and linearly to an applied field. Instead, they exhibit hysteresis, which means the magnetic flux density lags the applied field. That lag is part of what creates loss, heat, and efficiency limitations in real transformers, inductors, EMI filters, and high-frequency power electronics systems.

Fig. 1: Annotated hysteresis loop showing Bm, Br, Hm, Hc, and Core loss density

The key magnetic parameters engineers want

A proper magnetic characterization workflow usually begins with the basic B-H parameters:

• Bm: maximum magnetic flux density
• Br: residual magnetic flux density
• Hm: maximum magnetic field strength
• Hc: coercive force

From there, the analysis expands into performance-oriented quantities such as:

• Pc: core loss
• Pcv: core loss per volume
• Pcm: core loss per mass
• μa: relative permeability
• VA: apparent power
• Br/Bm: rectangular ratio
• 2Φm: total flux linkage

These values help engineers compare materials, optimize geometry, estimate thermal behavior, and understand how a core will behave across operating frequency and flux-density conditions.

Why core loss measurement is so important

In many applications, core loss is the parameter that most directly affects temperature rise, efficiency, and achievable power density. Core losses represent energy dissipated in magnetic materials and arise from several mechanisms, including hysteresis loss, eddy-current loss, and anomalous loss. The knowledge base defines core loss with the expression:

Pc = (N1/N2) × (1/T) × ∫ i1(t) V2(t) dt

From that base value, the analyzer can also determine:

• Pcv = Pc / Ve for loss per volume
• Pcm = Pc / We for loss per mass

These derived values are extremely useful when comparing materials of different dimensions or densities. For engineers selecting a core material for a converter, transformer, choke, or resonant design, this is the type of data that drives confident decisions.

Why phase angle accuracy matters so much

One of the most important takeaways from the knowledge base is that accurate core-loss measurement depends on precise determination of the phase difference θ between the induced voltage waveform and the excitation current waveform. Small phase errors can create significant core-loss calculation errors.

That point is easy to underestimate. In magnetic measurements, the loss component is often derived from very small phase-dependent differences between waveforms. If the phase relationship is even slightly off, the computed loss can move by a surprisingly large amount. That is why phase correction is not a “nice to have.” It is central to trustworthy loss data.

Why IWATSU uses the cross-power method

IWATSU B-H Analyzers use the Cross-Power Method, and the knowledge base notes that this method is compliant with IEC 62044-3 and supports highly accurate core-loss measurement up to 10 MHz. The same source contrasts it with other IEC-listed approaches such as the digitizing method and calorimetric method.

The cross-power method processes the measurement in a way that specifically addresses amplitude and phase-related error sources. According to the knowledge base, the method proceeds in four main steps:

1. Acquire the induced voltage and excitation current waveforms in the time domain
2. Convert those signals into frequency spectra
3. Compensate amplitude and phase errors from the current detection resistor on the frequency axis
4. Integrate to calculate core loss without phase-related errors

That is the heart of the IWATSU advantage in this context. The instrument is not simply “looking” at two waveforms. It is correcting for known measurement-chain effects before determining loss. For higher-frequency magnetic characterization, that distinction matters.

Why a general-purpose digitizer or oscilloscope alone is often not enough

The knowledge base makes a very practical point here. Without phase correction, the digitizer method does not compensate for the frequency response of the current detection resistor, which leads to error. It even gives an example that around 500 kHz, measurement error may reach roughly 20%. By contrast, the cross-power method compensates frequency-dependent phase errors and delivers significantly improved accuracy.

That does not mean oscilloscopes are not useful in the lab. They absolutely are. But it does mean that a general-purpose waveform instrument by itself is not the same thing as a dedicated magnetic analyzer with phase-corrected loss processing. When the goal is reliable core-loss characterization rather than a rough approximation, the measurement method becomes just as important as the hardware.

Normal Mode vs μ Mode

IWATSU B-H Analyzers are not limited to a single style of magnetic evaluation. The knowledge base distinguishes between Normal Mode and μ Mode, each serving a different engineering need.

Normal Mode

Normal Mode is the right place to start for classical hysteresis and loss characterization. Typical outputs include:

• Bm
• Br
• Hm
• Hc
• Pc
• Pcv
• Pcm
• μa
• VA
• phase angle

This mode is ideal when the goal is to understand the hysteresis loop, flux-density limits, coercivity, and magnetic loss.

μ Mode

μ Mode is more oriented toward impedance and permeability behavior. Typical outputs include:

• μ′
• μ″
• μz
• L
• R
• |Z|
• Q
• tanδ
• THD

This gives engineers access to information that is especially useful for frequency-dependent material behavior, loss mechanisms, impedance interpretation, and component optimization.

Complex permeability is also defined as:

μ = μ′ − jμ″

with μ′ representing the energy-storage component and μ″ the loss component, while the loss tangent is given by:

tanδ = μ″ / μ′

Fig. 2: Side-by-side Normal Mode vs μ Mode parameter graphic.

Measurement principle: how the analyzer builds B and H

The analyzer measures magnetic properties using two windings: a primary winding for excitation and a secondary winding for flux detection. The knowledge base summarizes the basic relationships as:

H = N1·I / le
B = (1/Ae) ∫ V dt

It also gives the 2-coil equations more explicitly:

B(t) = 1 / (N2 · Ae) · ∫ V2(τ) dτ
H(t) = N1 · i1(t) / Le = N1 · Vs(t) / (Le · Rs)

This is the foundation of the B-H curve: one part of the measurement tells you how strongly the material is being driven, and the other tells you how the material responds.

2-coil method vs 1-coil method

Another strong practical distinction in the knowledge base is the difference between 2-coil and 1-coil measurement.

In the 2-coil method, separate excitation and detection windings are used. The primary winding applies the alternating excitation current, and the secondary winding detects the magnetic flux density. The source notes that the secondary winding carries almost no current, allowing the setup to focus on core loss only. This makes the 2-coil method especially suitable for material evaluation.

In the 1-coil method, the winding used for excitation and flux detection is shared. According to the source material, that means the measured result contains iron loss plus copper loss, making it more appropriate for parts evaluation rather than pure material evaluation.

This distinction is extremely important in practice. If you are comparing raw magnetic materials, you usually want to isolate the material behavior as much as possible. If you are evaluating a finished magnetic part, copper loss becomes part of the real-world picture.

Fig. 3: 2-coil vs 1-coil diagram with “material evaluation” and “parts evaluation” labels.

Materials and applications

The knowledge base identifies a broad set of materials that can be evaluated, including:

• ferrites
• powder cores
• amorphous metals
• nanocrystalline alloys
• silicon steel
• transformer laminations

That makes IWATSU B-H Analyzers relevant across a wide range of engineering work, including:

• power electronics
• transformer design
• inductor development
• magnetic material research
• EMI filter design
• switching-loss optimization

For PMK America customers, this means the instrument can support both advanced materials work and very application-driven design tasks.

Advanced evaluation options

Beyond standard AC magnetic characterization, the knowledge base highlights several optional capabilities that expand what engineers can evaluate in one platform.

These include:

• DC bias measurement, with a maximum DC bias current of 30 A
• Sheet-shaped sample measurement for samples with length at least 36 mm, width up to 35 mm, and thickness up to 3 mm
• Temperature testing from −55 °C to +180 °C
• Scanner-based measurement for multiple samples

These options matter because many real magnetic systems do not operate at room temperature, under zero bias, or in only one sample geometry. The more closely a test setup matches real operating conditions, the more valuable the data becomes.

Why this matters for modern magnetic design

As switching frequencies rise and magnetic designs become more compact, the margin for measurement error shrinks. Engineers need better visibility into hysteresis behavior, loss mechanisms, permeability, impedance-related effects, and the impact of phase angle on calculated results. That is exactly where a dedicated phase-corrected B-H analyzer earns its place.

IWATSU B-H Analyzers combine classical hysteresis measurement with advanced signal processing and broad parameter extraction. The result is a platform that helps engineers move from “estimated magnetic behavior” to measured, defensible data across a wide frequency range.

Conclusion

A B-H analyzer is more than a tool for drawing hysteresis loops. In the right hands, it becomes a decision-making instrument for magnetic material selection, transformer optimization, inductor design, EMI work, and high-frequency loss analysis. IWATSU’s use of the cross-power method, phase-corrected processing, dual-mode parameter extraction, and support for advanced options such as DC bias and temperature testing make it a powerful solution for serious magnetic characterization.

At PMK America, we help engineers choose the right magnetic measurement approach for their application, sample type, and performance target.

Need help selecting the right IWATSU B-H Analyzer configuration for your lab or application? PMK America can help you evaluate frequency range, sample type, winding method, DC bias requirements, and advanced measurement options for meaningful magnetic characterization.

FAQ

What does an IWATSU B-H Analyzer measure?

It measures AC magnetic properties of soft magnetic materials and soft magnetic parts, including B-H curve, core loss, relative permeability, inductance, and complex permeability.

Why is phase angle important in core-loss measurement?

Because accurate core-loss calculation depends on the precise phase difference between induced voltage and excitation current. Small phase errors can cause significant loss-calculation errors.

What is the cross-power method?

It is the measurement method used by IWATSU B-H Analyzers for high-accuracy core-loss measurement. It acquires waveforms, converts them to frequency spectra, compensates amplitude and phase error, and then integrates to calculate core loss.

What is the difference between Normal Mode and μ Mode?

Normal Mode focuses on classical magnetic parameters such as Bm, Br, Hm, Hc, Pc, Pcv, Pcm, and μa. μ Mode focuses more on permeability and impedance-related outputs such as μ′, μ″, μz, L, R, |Z|, Q, tanδ, and THD.

What is the difference between the 2-coil method and the 1-coil method?

The 2-coil method uses separate excitation and detection windings and is suited to core-loss-focused material evaluation. The 1-coil method uses a common winding function and includes copper loss, making it more suitable for parts evaluation.

Can IWATSU B-H Analyzers support DC bias, single-sheet, and temperature testing?

Yes. The IWATSU B-H Analyzer has optional DC bias, single-sheet, and temperature scanner accessory components, supporting up to 30 A and temperature testing from −55 °C to +180 °C, as well as sheet-sample measurement and scanner-based multi-sample testing.

Is the IWATSU B-H Analyzer single-sheet tester based on an Epstein frame?