Author:
Herman vanEijkelenburg, Director of Marketing, Pacific Power Source
Date
07/05/2022
PDF
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Figure 1. Electric Vehicle Testing
Besides costs, one of the major obstacles for most consumers preventing them from adopting electric vehicles over IEC vehicles is range anxiety. Although great strides have been made in efficient energy conversion and battery power density, a typical range of 200 to 300 miles for most EV’s is still less that that of an entry level ICE vehicle which can be purchased for considerably less money. See Figure 1.
Another adoption barrier is re-charge time. As range is extended by using ever larger battery packs, the associated re-charge times increase as well. Even with the proliferation of fast public DC charging stations deploying ever increasing DC voltage charging levels, a typical recharging stop still takes 20 to 40 minutes for an 80% charge.
The automotive industry is working hard to address these issues but as EV market share increases, the cost of battery materials - which had been declined over the last decade - is going back up as more EV and Battery manufacturers compete for the scarce materials needed battery manufacture EV batteries.
Power Conversion Efficiency increases Range
Other than ever increasing battery size and hence cost, optimizing all stages of power conversion can maximize actual driving range by reducing losses. To do so, all components of the electric drive train need to be scrutinized and thoroughly tested. The same applies to on-board as well as off-board charging systems which also contribute to power conversion losses.
Figure 2 lists several of these power conversion and EV charging subsystems found in modern Electric Vehicles.
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Figure 2. EV System Components
An effective test and measurement strategy that utilizes a mix of test equipment, power sources and loads is a key requirement for successful EV infrastructure development and growth. Since future test requirements are not always easy to predict of extrapolate, choosing flexibly power test equipment can protect again future obsolescence.
Flexible, Multi-Function Test Equipment
For an effective test strategy, having a toolbox of flexible, multi-purpose test equipment can save cost and time as well as eliminate the need to replace test equipment often. A good example of this flexibility is the new regenerative AC and DC power source and load combination AZX Series. The AZX series is fully regenerative, allowing 100% of the absorbed energy in load or current sink mode to be returned to the power grid, it also supports both AC, DC and AC+DC combination testing. In addition to sourcing and sinking power, it can also be operated in electronic load mode for both AC and DC applications. In a sense, the AZX Series is the Swiss Army Knife of Power Testing. See Figure 3.
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Figure 3. AZX Series Regenerative AC Grid Simulators
Surrounding the EUT During Functional Testing
The concept of testing bi-directional or conventional power conversion equipment revolves around the use of regenerative AC and DC sources and loads to minimize the overall power needed to test the units under test. This is illustrated in Figure 4 where one AZX unit provided power and the second AZX acts as the energy recovering DC load. In this example, the unit under test is a bidirectional DC charging station.
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Figure 4. AZX Series Multi-Function Diagram
The AZX simulates any AC Grid condition that can occur in many utility grids to ensure immunity of the unit under test to international standards. The AZX that operates as a DC load can return all energy provided by the DC output of the charger back to the utility gird, thus greatly reducing the amount of losses and heat that would be associated with the use of conventional, dissipative DC loads.
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Figure 5. Regenerative Electric Vehicle Charger Test Setup
The built in frequency, voltage or current transient programming capabilities of the AZX allow any type of grid power anomaly such as brown-outs, voltage dips or surges and other transient phenomena to be simulated to test AC powered sub systems for immunity. The same AZX can also be used as part of a power compliance test system with the addition of an EMC Test System (ECTS2) cabinet.
