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Yokogawa releases a high-voltage differential probe

Yokogawa releases a high-voltage differential probe

New Products |
By Jean-Pierre Joosting



Yokogawa Test & Measurement Corporation has released its PBDH0400 series differential probe with a maximum input voltage of 2000 V and a frequency bandwidth of 400 MHz.

The differential probes can deliver the measurements required for developing the next generation of higher-speed power devices, such as power devices that use SiC or GaN technology. SiC, for example, requires the ultra-precise measurement of high-voltage and higher-speed signals. Such next-generation power devices are especially relevant for reducing energy consumption through improved energy efficiency.

For example, the differential probes enable precision evaluation of high-speed, high-voltage switching signals exhibited by SiC devices and IGBTs within EV inverters. They are also ideal for power analysis of SiC and GaN power devices as well as testing industrial devices, including motors, robots, and sensors.

Two models of the PBDH0400 series of  differential probes will initially be available — the 702922 with a maximum input voltage of 2000 V, and the 702921 with a maximum input voltage of 1000 V.

In automotive applications, to accurately observe faster-changing signals prevalent in electric vehicle (EV) and clean energy applications, the PBDH0400 series differential probe measure voltages over 1000 V and offer a wide frequency range from DC to 400 MHz. This capability is particularly useful for developers of next-generation inverters. Further, high noise resistance allows the detection of events that can cause unexpected anomalies, including waveform overshoot and ringing.

The PBDH0400 series features the Yokogawa probe interface, saving both cost and installation space by eliminating the need for an external power supply when connected to a Yokogawa oscilloscope, such as the 12-bit DLM5000HD or DLM3000HD. Furthermore, the probe attenuation ratio is automatically set through the interface so that measurement can start immediately after connection to the instrument.

Some typical applications include automotive inverters and motors, household appliances, industrial equipment and power electronics.

 

Applicaton example — inverters in EVs

In EVs, battery power is converted using inverters to drive the motor or motors (three-phase AC). The primary challenge is to reduce the switching loss during power conversion. Yokogawa explains the process and issues as follows.

“To assess the switching loss, engineers must check the transition time of the voltage and current waveforms in the OFF to ON transition region.

“However, for switching devices such as SiC and GaN, the transition time between OFF to ON is faster than ever before, so the measurement system requires a higher frequency bandwidth. To provide some context, a measurement system with a bandwidth of 350 MHz or higher is necessary to measure a 1 ns transition time. In addition to the frequency band of the waveform measuring instrument, the probe that draws the signal from the device under test also needs a high-frequency band.

“Take the example of an inverter that drives a three-phase motor, where the gate-source voltage (Vgs) on the high side is the switching command itself. Say the engineer in this scenario observes the voltage waveform between two points with a so-called ‘floating potential’ that is not ‘ground potential’ in the circuit configuration.

Due to this floating potential, a differential probe is necessary to observe Vgs, but the problem is that fluctuations in the floating potential affect the measurement results and prevent correct waveform observation. In general, the higher the frequency band, the worse this effect becomes. It is therefore necessary to deploy differential probes that are less susceptible to fluctuations in floating potential, namely by offering a good common-mode rejection ratio (CMRR).

“For this reason, the new Yokogawa PBDH0400 series high-voltage differential probes feature superior CMRR and excellent frequency response flatness characteristics.

“Another important point involves attenuation. To improve test accuracy and/or increase measuring range, the ratio of attenuation – which reduces the power of a signal without distorting its waveform — is 500:1/50:1 (702921 model) or 1000:1/100:1 (702922 model). A common issue here is inadvertent errors introduced by the engineer during manual setting processes. However, the availability of a switch on the probe head of PBDH0400 series differential probes means the attenuation ratio can be selected, automatically recognized, and configured (along with the input impedance setting).

“Ensuring probe suitability for a wide range of important measurement tasks, users can complement the included pincher tip by choosing from an expanded range of optional accessories according to the measurement target.”

https://tmi.yokogawa.com

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