Hillcrest ZVS Technology Demonstrates More Than 90% Reduction in Motor Voltage Spikes

Below 1 MHz, emissions were comparable to the conventional inverter despite reductions at higher frequencies.

Rhea-AI Summary

Hillcrest Energy Technologies (HLRTF) reported peer-reviewed tests showing its ZVS inverter cut motor-terminal voltage overshoot by more than 90%.

With an 80-kW motor, a 2-meter shielded cable, 400 V DC and 20 kHz switching, peak motor-terminal voltage fell from 1.5 to 1.04 times DC-link voltage against a conventional hard-switched silicon carbide inverter. In a separate test at 470 V DC and 40 kHz, voltage slew rate fell from approximately 16 to approximately 1.4 V/ns, while emissions above 5 MHz were approximately 25 dB lower. With a 50-meter cable at 470 V DC, peak load voltage was approximately 920 V in a double-pulse test, below twice DC-link voltage.

The paper was accepted for IEEE ECCE 2026. Motor-overvoltage findings apply to cable-fed drives. Hillcrest says the emissions and slew-rate findings do not depend on cable length. For the configuration analyzed, ZVS extended the critical cable length to approximately 18 meters.

Positive

• Minor pointMotor-terminal voltage overshoot fell more than 90%, from 1.5 to 1.04 times DC-link voltage in the 2-meter-cable test.
• Minor pointVoltage slew rate fell from approximately 16 to approximately 1.4 V/ns at 470 V DC and 40 kHz.
• Minor pointEmissions above 5 MHz were approximately 25 dB below the hard-switched inverter reference.
• Minor pointEmissions between 1 and 5 MHz were 5 to 25 dB below the hard-switched reference.
• Minor pointPeak load voltage remained below twice DC-link voltage at approximately 920 V in the 50-meter-cable double-pulse test.

2 minor points

• Minor pointCritical cable length extended to approximately 18 meters for the configuration analyzed.
• Minor pointPeak inverter efficiency reached up to 99.7% in separate, previously reported testing.

Negative

• Minor pointEmissions below 1 MHz were comparable between ZVS and the hard-switched inverter.
• Minor pointMotor-overvoltage findings apply to cable-fed drives; the effect varies with cable length.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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VANCOUVER, BC / ACCESS Newswire / September 29, 2026 / Hillcrest Energy Technologies (CSE:HEAT)(OTCQB:HLRTF)(FSE:7HI) ("Hillcrest" or the "Company") today announced peer-reviewed test results quantifying the performance of its zero-voltage-switching (ZVS) inverter technology against a conventional hard-switched silicon carbide (SiC) inverter. In side-by-side testing, ZVS reduced motor-terminal voltage overshoot by more than 90%, from 1.5 per unit (p.u.) to 1.04 p.u. of DC-link voltage and reduced high-frequency electromagnetic interference (EMI) above 5 MHz by approximately 25 dB.

The results are documented in a peer-reviewed paper accepted for the IEEE Energy Conversion Congress and Expo (ECCE 2026), a leading international conference in power conversion. Dr. Emanuel Serban, Hillcrest's Vice President of Engineering, will present the paper at the event, to be held October 4-8, 2026, in Vancouver, BC.

Commercial Significance

Drive manufacturers are moving from silicon to wide-bandgap semiconductors, principally SiC, to gain efficiency, switching frequency and power density. The paper documents the engineering penalty that accompanies this transition: because SiC devices switch far faster than silicon, impedance mismatch between inverter, cable and motor produces repeated voltage reflections, and motor-terminal voltage can reach twice the DC-link voltage even with cable lengths of only a few meters.

The consequences carry commercial weight. The paper states that these voltage oscillations accelerate insulation aging, promote partial discharge activity and ultimately lead to premature failure of inverter-fed motor windings, which translates into warranty exposure for equipment makers and unplanned downtime for end users. The standard mitigation is passive filtering at the motor terminals or the inverter cabinet. As the paper notes, while such filters are effective, they add cost and size to the drive system and incur extra power losses, which offsets the inherent advantages of wide-bandgap technology.

Hillcrest's ZVS approach addresses the problem at the switching event rather than downstream of it. By commutating each device when the voltage across it is near zero, the platform extends the voltage transition roughly tenfold while preserving high efficiency, whereas conventional slew-rate reduction through snubber circuits increases switching losses and degrades efficiency. For drive OEMs evaluating SiC platforms, these results provide a quantified basis for comparing ZVS against added filtering hardware.

Where the Results Apply

The overvoltage findings apply to cable-fed drive systems, where the inverter is cabinet-mounted and connected to the motor by a cable of meaningful length. The effect scales with cable length, so the benefit is greatest in factory automation and robotics, conveyor and material handling systems, packaging machinery, automated assembly lines, cabinet-driven industrial pumps and fans, and electric vehicle and rail traction systems.

The emissions and slew-rate results are independent of cable length and apply to any SiC inverter platform.

Detailed Findings

Against a conventional hard-switched SiC inverter, the ZVS platform delivered:

• Overshoot reduction of more than 90%. Motor-terminal overshoot fell from 1.5 p.u. to 1.04 p.u. with an 80-kW motor on a 2-meter shielded cable at 400 V DC and 20 kHz. Overshoot is the peak voltage the motor insulation actually sees, expressed relative to DC-link voltage.
• An order-of-magnitude reduction in dv/dt. Slew rate fell from approximately 16 V/ns to 1.4 V/ns at 470 V DC and 40 kHz. Because inverter output voltage rise time has been shown to have a dominant influence on the severity of reflected-wave overvoltage, this is the mechanism behind the overshoot result.
• Up to 25 dB lower high-frequency emissions. Above 5 MHz, emissions were roughly 25 dB below the hard-switched reference. Between 1 and 5 MHz, the ZVS platform's emissions were 5 to 25 dB lower; below 1 MHz the two platforms were comparable. Reduced high-frequency content is where EMI filtering and shielding costs concentrate.
• Controlled voltage on long cable runs. Under worst-case double-pulse conditions with a 50-meter cable at 470 V DC, peak load voltage remained below 2 p.u. at approximately 920 V. The paper notes that published research reports hard-switched inverters exceeding 2-3 p.u. under comparable narrow-pulse conditions.

Slower switching transitions also allow longer cables. Every drive has a critical cable length, beyond which reflected waves can double the voltage at the motor. For the configuration analyzed, ZVS extends that limit to approximately 18 meters, giving machine builders more flexibility in cable routing and cabinet placement.

Results at a Glance

Parameter	Conventional hard-switched SiC	Hillcrest ZVS	Test conditions
Motor-terminal overshoot	1.5 p.u. (+50%)	1.04 p.u. (+4%)	80 kW motor, 2 m shielded cable, 400 V DC, 20 kHz
Voltage slew rate (dv/dt)	~16 V/ns	~1.4 V/ns	470 V DC, 40 kHz, modulation index 0.4
Switching voltage rise time	~30 ns	~335 ns	470 V DC, 40 kHz, modulation index 0.4
Emissions, 1-5 MHz	Reference	5-25 dB lower	FFT, 470 V DC, 40 kHz, modulation index 0.4
Emissions above 5 MHz	Reference	~25 dB lower	FFT, 470 V DC, 40 kHz switching frequency
Motor-terminal overshoot using long cables	Literature reports >2-3 p.u.	~920 V (<2 p.u.)	Double-pulse test, 470 V DC, 50 m cable-fed

Source: E. Serban, J. Amini, M. Kroesser and C. Lascu, "High-Performance ZVS Inverter for Traction Systems Under Reflected Wave Conditions," Proceedings of IEEE ECCE 2026.

Broader ZVS Platform Results

The reflected-wave findings build on the results Hillcrest has previously reported for its ZVS technology in separate testing and research:

• Efficiency: up to 99.7% peak inverter efficiency, confirmed in testing at the facilities of global automotive OEMs and Tier One suppliers^[1]. This indicates that the controlled switching transitions described in the paper are compatible with very high efficiency.
• Electromagnetic interference: chamber testing at a certified external laboratory selected by a European automotive OEM found substantially lower EMI than conventional inverters across all tested operating points^[2].
• Passive component reduction: by largely eliminating switching losses, ZVS supports higher switching frequencies, which Hillcrest's published research has shown reduced DC-link capacitor size and ripple-related heating, with benefits for drive cost, volume and component lifetime^[3].

Together with the ECCE 2026 results, these findings indicate that ZVS can address efficiency, electromagnetic interference and motor insulation stress within a single architecture. Drive designers often have to trade these attributes off against one another.

Management Commentary

"Reflected-wave overvoltage limits the use of high-efficiency, high-speed power semiconductors in motor drives with long cables. Conventional solutions require additional filters, increasing system cost, size, and complexity. Our solution simplifies the drive design while enabling the use of advanced, high-efficiency semiconductor devices," said Dr. Emanuel Serban, Vice President of Engineering at Hillcrest Energy Technologies. "Controlling dv/dt at the switching event removes the cause instead of treating the symptom. Both theoretical analysis and experimental results demonstrate a significant reduction in EMI and motor-terminal overvoltage in cable-fed systems."

"Peer-reviewed validation is what drive manufacturers require before committing to a new power conversion architecture," said Don Currie, CEO of Hillcrest Energy Technologies. "Presenting these results puts quantified evidence in front of exactly the engineering audience that makes those decisions. Combined with the efficiency and EMI performance already demonstrated in OEM testing, these results strengthen the case for ZVS across a broad range of motor-drive applications."

About the Research

The paper, "High-Performance ZVS Inverter for Traction Systems Under Reflected Wave Conditions," originated in electric vehicle traction work and applies to any cable-fed motor drive. Test setup: three-phase inverter using 1200 V SiC MOSFETs driving an 80 kW motor through a 35 mm² four-conductor shielded cable (0.3 µH/m, 130 pF/m, characteristic impedance approximately 48 Ω, propagation velocity approximately 160 m/µs).

Authors: Dr. Emanuel Serban and Jalal Amini (Hillcrest Energy Technologies Ltd., Canada); Mathias Kroesser (Systematec GmbH, Germany); Prof. Cristian Lascu (Politehnica University of Timișoara, Romania). The paper will be published in the IEEE ECCE 2026 Proceedings and will be available on IEEE Xplore following the conference.

More information on IEEE ECCE 2026: https://www.ieee-ecce.org/2026/

About Hillcrest Energy Technologies

Hillcrest Energy Technologies Ltd. is a Canadian clean technology company developing advanced power conversion technologies and digital control systems for next-generation energy applications, including AI datacenters, energy storage, industrial motor drives, microgrids, and electric-vehicle powertrains. The PCS1000 is Hillcrest's newest product platform, currently in the A-Sample prototype stage. For more information: https://hillcrestenergy.tech/

CONTACT INFORMATION

Investor Relations
Don Currie
info@hillcrestenergy.tech
O: +1 604-609-0006
Toll-free: 1-855-609-0006

Public Relations
Jamie L. Hogue
jhogue@hillcrestenergy.tech
O: +1 602-793-9481

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FORWARD-LOOKING INFORMATION

Cautionary Statement Regarding "Forward-Looking" Information

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[1] As announced by the Company on December 16, 2024.

[2] As announced by the Company on March 4, 2024.

[3] Hillcrest white paper, Benefits of High-Switching Frequency on DC-Link Capacitors, August 17, 2022.

SOURCE: Hillcrest Energy Technologies Ltd.

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FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

When will Hillcrest Energy Technologies' ZVS inverter paper be available?

The paper will be published in the IEEE ECCE 2026 Proceedings and will be available on IEEE Xplore following the October 4–8, 2026 conference.

How did Hillcrest's ZVS inverter emissions compare at lower frequencies?

Between 1 and 5 MHz, emissions were 5 to 25 dB below the conventional hard-switched inverter reference. Below 1 MHz, emissions from the two platforms were comparable.