The Benefits of the PCR-WEA Series of AC Programmable Power Supplies
Switching AC power supplies are required for a wide range of testing scenarios including motors, home appliances, power supplies, avionics, servers, and more. For a high accuracy test, a high-quality direct and alternating current must be supplied with little-to-no distortion to function as an ideal voltage source. On top of this, these supplies should ideally allow users to replicate any waveform necessary to easily accomplish compliance testing. This requires a multifunctional programmable power supply with custom waveform banks for easy test simulation—a quality that enables rapid and precise production tests for highly regulated electronics systems such as avionics, industrial power, and automotive systems.
This article explores the new PCR-WEA series offered by Kikusui and how these programmable AC power supplies are able to meet the stringent test demands of electronics components with its built-in features, compact size, and parallel operation while also lowering the barriers for test setup with its waveform banks and intuitive control of voltage and frequency.
The benefits of a wide output range and high accuracy DC and AC output in a small, accessible package
Polyphase, high power AC supply
The PCR-WEA includes a 15 module line-up with power ratings ranging from 1 kVA to 36 kVA. The series can include support for 1-phase, 1-phase split (1-phase 2-wire or 2-phase), as well as 3-phase, all in one unit as shown in the specifications in Figure 1.
Figure 1: Specifications for the PCR-WEA AC programmable power supply.
The multi-phase power supply simplifies testing where there is no need for additional setup when going from single- to three-phase applications. With this capability, the system can simulate various conditions and phenomena occurring in the AC power environment for compliance testing. This includes immunity tests of electrical and electronic equipment when subjected to harmonics, voltage fluctuations, variation in power supply frequency, sudden voltage drops, ripples at the DC input power terminal, and more. Many of these compliance tests require testing with a rated current up to 16 amps per phase at high disturbance frequencies. This not only requires a multi-phase output AC power supply, but also the ability to simulate these power line abnormalities successfully--a subject that will be touched upon later in this article. The high AC output and wide output range (1 to 160Vac/2 to 320 Vac) also extends the potential testing use cases the singular power supply can serve.
High accuracy output
The PCR-WEA has a high accuracy output with a high line regulation, load regulation, low ripple noise, low ambient temperature variation, low total harmonic distortion (THD), a fast transient response, and a fast response speed (Figure 2).
Figure 2: The output voltage stability of the PCR-WEA.
The quality of power line simulation also relies on a high accuracy output. Even without this type of simulation testing, a distorted output waveform can and will deteriorate production throughput. These specs are comparable to the linear power supply that is known for its accuracy in delivering power with low noise. Utilizing a power supply that produces very little ripple current or noise allows for users to address, in finer detail, the potential issues with their device under test (DUT).
For example, isolating vibration issues in motors can be tricky as the noise within the “output torque” waveform can contain ripples from the inverter that supplies power to the motor, or, from the motor itself (Figure 3). In order to accurately assess the torque performance of the motor itself, it is best to use a power supply that outputs as little distortion as possible. However, this power supply supports many more added features to expand its testing capabilities.
Figure 3: A sample test set up where it is difficult to discern whether the ripple in the output torque is caused by the motor’s inverter or the motor itself. An AC power supply with little distortion is needed to accurately discern where the issue in the output waveform is coming from.
5 kHz output
This system has a maximum output frequency up to 5 kHz, this is particularly high and can be of high utility, especially in critical applications in the defense and avionics industries. For instance, the frequency performance allows for simulation of the sharp voltage fluctuations required in airborne electronic equipment testing. The IEC 61000-4-13 also requires a rated current up to 16 A per phase at disturbance frequencies up to 2.4 kHz for harmonics and interharmonics on low voltage power networks.
And, since the output current is reduced by the output frequency, it is useful to have that much flexibility in both the power and frequency of a power supply.
Kikusui was able to reduce the form factor of the PCR-WEA by 60% compared to previous PWM models while also increasing its efficiency by 7%. This compact size allows the device to be easily built into the production line and integrated into test systems for R&D. The compact 6kVA/6U form factor allows for the easy preparation of an automated, one-rack testing system without requiring a costly, specialized power source installation space (Figure 4). As with any job, not having the right tools can lead to a great deal of frustration and stifle progress. The multi-function, high performance and high capacity AC source creates a much more inviting test environment that can be configured to multiple test environments, saving space and precious engineering resources.
Figure 4: The 6kVA PCR-WEA power supply sits in a compact 6U form factor at 43 kilograms, the lightweight programmable power supply can be easily integrated into test systems.
Standard interfaces to support automation
The PCR-WEA series includes a flexible digital interface for users utilizing LAN, USB, and RS232C communication interfaces with a GPIB factory option as well. The LAN connection is LXI compliant, allowing you to monitor and control your device wherever you are via computer, smartphone, or tablet web browser. This LAN interface can potentially be connected to a Wi-Fi router in order to enable wireless LAN. The PCR-WEA can also be controlled directly with easy remote-control software for users that have limitations in external communication (Figure 5). These features are particularly useful for controlling/monitoring tests that need to be conducted at a distance. Critical AC tests that are performed in anechoic chambers and shielded rooms will, for instance, need the monitoring and remote control to be outside of the room.
Figure 5: The PCR-WEA features an LXI-compliant LAN interface as well as remote-control software for users that want to remotely control/monitor their test equipment at a distance.
Paralleling units to increase capacity and widen test applications
Units can be parallels for a maximum capacity of up to 144 kVA (four 36 kVA models in parallel). Parallel operation does require the user to repeatedly implement the same model. Instead different power capacities (i.e., models) can be combined to increase the capacity of the overall system. This expands testing capabilities greatly where the user is not limited by the power output of a singular model or by owning two separate models (Figure 6).
Figure 6: The PCR-WEA series can be combined with up to 4 units with different capacity models for parallel operation to expand the power.
The complexities of compliance testing
The PCR-WEA supports easy compliance testing with built-in features such as:
- Power line abnormality simulation
- Sequence operation
- Custom waveform banks
Power line abnormality simulation
The PCR-WEA/WEA2 series can simulate various power line abnormalities such as power outages, voltage drops (dips) and voltage increases (pops). This feature is useful for immunity testing of electrical and electronic devices that are connected to a low voltage distribution system or have DC power input ports such as the testing of power-source switches (Figure 7).
Figure 7: The PCR-WEA can simulate various power line abnormalities, including power outages and fluctuations in voltage.
When combined with a KHA3000 harmonic/flicker analyzer, LIN Series line- impedance network, DSI series IEC dip simulator and application software, the PCR-WEA can be the cornerstone to tests that conform to IEC and JIS standards (Figure 8).
Figure 8: The single- and three-phase PCR-WEA can be used for IEC and JIS compliance testing of electrical and electronic devices.
Application software (i.e., Quick Immunity Sequencer 2) is available to test in accordance with the specifics listed in the various immunity tests within the IEC 61000-4 power line disturbance standard (Figure 9). Not only can this software be used for compliance testing based on the latest standards (or for some types of preliminary testing), but the software can be also employed for advanced checking in the development phases as well as for immunity margin tests, because it allows extended testing conditions to be set as needed.
Figure 9: List of conformance to the EMC standard tests.
This feature is not only useful in low voltage distribution system testing but also for testing the high voltage systems used for EV charging where the PCR-WEA can be used to test both fast charging systems that use direct current and residential charging using the EV’s onboarding charger (OBC) (Figure 10).
Figure 10: High voltage and large capacity DC Power line disturbance and immunity testing for EVs in fast DC charging and AC charging.
Custom waveform banks
The custom waveform banks within the PCR-WEA supports both military (MIL-STD-704A/E/F) and civilian (RTCA DO-160F/G and JIS W0812:2004) standards for avionics. Both the military and civilian avionics follow strict guidelines and procedures for testing. All electrical components and parts installed on the fuselage must be in compliance with these standards, aircraft manufacturers also often have their own private standards as well. The avionics test software (SD012-PCR-LE/WE) includes a library of test patterns that can be easily run by selecting the wiring configuration and the type of test. This software greatly simplifies the testing process making testing easy, quick and accurate.
The SD032-PCR-WE is also application software that can be used with the PCR-WEA to create and edit sequences visually with a mouse and without programming (Figure 11). This lowers the barriers for creating and managing custom test conditions and arbitrary waveforms--enhancing the flexibility and usability of this device. This can be helpful for instance, in EV motor testing where engineers can program complex waveforms and then intuitively control both voltage and frequency on the front panel to emulate the voltage supplied by the motor controller.
Figure 11: Application software (SD032-PCR-WE) available for custom sequence generation.
Power regeneration for green power supply testing
Some models within the PCR-WEA series have an internal regeneration technology that allows for 100% reuse of reverse power flow, rather than discharging it and dissipating it as heat—a feature that lead to energy savings for the testing of batteries, motor, inverters, micro inverters, converters, and transformers (Figure 12). If the DUT is a battery, for example, the charge/discharge testing of that battery can be performed without switching connections, with the added benefit of resupplying that waste energy back to the grid. An additional power saving mode allows the power unit to go into a low current “sleep mode” when it does not detect output for a certain amount of time. These features combined reduce the overall power consumption of plant operations and overall environmental impact.
Figure 12: The PCR-WEA2R models are capable of 100% power regeneration with absolutely no reverse load flow time limit.
The PCR-WEA is a multi-functional, high capacity and high performance programmable AC power supply. The compact, power dense package produces a very low distortion output for precise testing. A 5 kHz output meets the accuracy of a linear power supply with the flexibility of the programmable power supply. The power supplies can also be paralleled to increase power capacity of the power supplies. Further flexibility can be found in the customizability of the PCR-WEA series and its support software, allowing for compliance testing for consumer, military and civilian avionics as well as automotive devices ranging from tests for low voltage distribution systems to high voltage charging systems. The series also supports regeneration; this feature enables significant power savings when testing DUTs that will reverse power flow back to the source.