With a view to check a number of ICs concurrently with totally different check voltages and currents, semiconductor automated check tools (ATE) makes use of a number of supply measurement models (SMUs). Every SMU requires its personal impartial floating voltage monitoring energy provide to make sure clear measurements.

Determine 1 exhibits the fundamental construction of the SMU energy provide. The voltage monitoring energy provides want to produce the facility amplifiers with a large voltage vary (±15 V to ±50 V) and a relentless energy functionality.

Determine 1 A simplified power-supply block diagram in an ATE. Supply: Texas Devices

Determine 2 illustrates the utmost steady-state voltage and present that the SMU requires in pink and the pulsed maximums in blue.

Determine 2 An instance voltage-current profile for a voltage monitoring energy provide. Supply: Texas Devices

The ICs below check require a low-noise energy provide with minimal energy loss. With a view to handle the facility dissipation in a linear energy machine and ship fixed energy below the circumstances proven in Determine 2, it’s required that the facility provide be capable of generate a pulsating output with excessive instantaneous energy.

Along with energy dissipation issues, it’s important that the facility provide has a adequate effectivity and thermal administration to accommodate as many check channels as doable.

4 topologies are studied and in comparison with see which one finest meets the voltage monitoring energy provide necessities. Desk 1 lists {the electrical} and mechanical specs for the facility provide. The 4 topologies into account are: hard-switching full bridge (HSFB), full-bridge inductor-inductor-capacitor (FB-LLC) resonant converter, twin lively half bridge (DAHB), and a two-stage method composed of a four-switch buck-boost (4sw-BB) plus half-bridge LLC resonant converter (HB-LLC).

Desk 1 Electrical and mechanical SMU necessities. Supply: Texas Devices

Topology comparability

Determine 3 exhibits the schematic for every of the 4 energy provides.

Determine 3 The 4 topologies evaluated to see which one finest meets the voltage monitoring energy provide necessities listed in Desk 1. Supply: Texas Devices

Every topology was evaluated on two important necessities: small measurement and minimizing the thermal footprint. Effectivity is simply necessary in so far as warmth administration is worried.

Desk 2 summarizes the potential advantages and challenges of every topology. Along with measurement, the utmost top constraint necessitates a printed circuit board (PCB)-based transformer design.

Desk 2 The advantages and challenges of the 4 totally different SMU energy provide topologies. Supply: Texas Devices

With a view to perceive the scale implications for the HSFB, it’s crucial to start out out by analyzing the construction of the transformer. Equation 1 calculates the turns ratio for the HSFB as:

Utilizing the necessities listed in Desk 1 offers a results of . As a result of a sensible design would require a PCB with not more than 18 layers, the utmost required main activates a center-tapped design is 2:8:8. With this data, you should utilize Equation 2 to estimate the middle leg core diameter:

Exhausting switching losses within the FETs will maintain the frequency no larger than 500 kHz, leading to a 12 mm diameter of the middle leg. The ensuing core will likely be not less than twice this measurement. The top result’s that the HSFB answer is simply too giant for any critical sensible consideration.

The only-stage FB-LLC permits the next switching frequency by fixing the hard-switching issues discovered within the HSFB. Nevertheless, the broad enter and output voltage vary would require a small magnetizing inductance. The very best design recognized used a turns ratio of 4:5, L_m = 2 µH, L_r = 1 µH, and f_r = 800 kHz. This design addresses the problems with the HSFB by incorporating extra main turns, attaining a excessive working frequency for minimal measurement, and requiring solely 14 layers. Nevertheless, the design suffers from a number of working factors that end in ZVS loss and an incapacity to generate the required output voltage below pulsed load circumstances.

Determine 4 exhibits the equation and plots of the utmost achieve of the system. Supporting the necessities outlined in Desk 1 requires a achieve of not less than 3. Determine 4 exhibits that that is solely doable by drastically reducing a number of of L_r, L_m, or f_r. Reducing L_r will end in a lack of ZVS from the speedy change within the inductor present. Lowering f_r will drive up the scale of the transformer and the required main turns. Reducing L_m will considerably enhance losses from further circulating present. Given these elements, the single-stage FB-LLC can be not an choice.

Determine 4 Most basic harmonic approximation (FHA) achieve plots. Supply: Texas Devices

DAHB

The DAHB [1] is an attention-grabbing choice that additionally makes an attempt to resolve the hard-switching issues. One space of concern is the requirement to have lively management of the secondary FETs. This sort of management would require further circuitry to translate the management throughout the isolation boundary. Equation 3 predicts the ensuing energy supply functionality of the DAHB:

Desk 3 lists the outcomes for the complete necessities outlined in Desk 1. Discover that there are a number of problematic circumstances, most notably one situation the place the required peak present is 80 A. The FETs used within the design can not accommodate this present.

Desk 3 DAHB working factors with a number of problematic circumstances that can’t be designed. Supply: Texas Devices

The 2-stage method pushes the voltage regulation downside to the 4sw-BB and operates the HB-LLC at a set frequency at resonance, which permits the HB-LLC to run at excessive frequency and extra simply obtain ZVS below all circumstances. The apparent draw back of this method is that it makes use of two energy levels as an alternative of 1. Nevertheless, the decreased currents within the HB-LLC and its capability to run at larger frequencies allow you to attenuate the scale of the transformer.

Desk 4 summarizes the comparability between the 4 topologies, highlighting the explanations for choosing the two-stage method. References [2] and [3] describe some important management parameters used for the buck-boost and LLC.

 Desk 4 Comparability between the 4 totally different topologies, highlighting the explanations for choosing the two-stage method. Supply: Texas Devices

Take a look at outcomes

Primarily based on the comparability outcomes, I constructed a high-power-density (14 mm by 45 mm) 4sw-BB plus HB-LLC prototype. Determine 5 exhibits a picture of the {hardware} prototype of the ultimate design that matches within the house outlined by Desk 1.

Determine 5 The highest-side format of the high-power density 4sw-BB + HB-LLC check board. Supply: Texas Devices

Determine 6 exhibits each effectivity and thermal efficiency of the LLC converter.

Determine 6 The LLC effectivity curve and a thermal scan of the LLC converter. Supply: Texas Devices

Two-stage method

After contemplating 4 topologies to satisfy ATE SMU necessities, the two-stage method with the four-switch buck increase and fixed-frequency LLC was the smallest total answer able to assembly the system necessities.

Brent McDonald works as a system engineer for the Texas Devices Energy Provide Design Companies crew, the place he creates reference designs for a wide range of high-power functions. Brent acquired a bachelor’s diploma in electrical engineering from the College of Wisconsin-Milwaukee, and a grasp’s diploma, additionally in electrical engineering, from the College of Colorado Boulder.

Associated Content material

• Energy Ideas #140: Designing a knowledge middle energy structure with provide and processor rail-monitoring options
• Energy Ideas # 141: Ideas and tips for attaining broad working ranges with LLC resonant converters
• Modular scalable check set contains source-measure ATE
• ATE system automates energy semiconductor checks

References

1. Laturkar, N. Deshmukh and S. Anand. “Twin Energetic Half Bridge Converter with Built-in Energetic Energy Decoupling for On-Board EV Charger.” 2022 IEEE Worldwide Convention on Energy Electronics, Good Grid, and Renewable Power (PESGRE), Trivandrum, India, 2022, pp. 1-6, doi: 10.1109/PESGRE52268.2022.9715900.
2. McDonald and F. Wang.” LLC efficiency enhancements with frequency and part shift modulation management.” 2014 IEEE Utilized Energy Electronics Convention and Exposition – APEC 2014, Fort Value, TX, USA, 2014, pp. 2036-2040, doi: 10.1109/APEC.2014.6803586.
3. Solar, B. “Multimode management for a four-switch buck-boost converter.” Texas Devices Analog Design Journal, literature No. SLYT765, 1Q 2019.

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