Hello again everyone!
We’re very lucky today in being able to show off what we have for a preliminary design for our electrical system for Whio II. The specification represents a new approach to solving the issues of a zero-emissions yacht.
From a safety and reliability aspect, the two hulls are a mirror image of one another, so that a single issue does not compromise the entire system. However, power can be used from either battery bank (on either side), and a single engine has enough power to get you back to safety.
There’s no gearbox as they contain oil, so the electric motor/generator operates at peak torque at 700rpm, and there is a direct link from the prop to the motor.
Also, you may notice that there are several inverters, one for each major electric load, such as house loads, water, tender charging, and one for each driveline. This actually lowers weight and helps the system cope with heavy use. We have a 7.5kW sauna system and a large 7.5kW induction hob and BBQ, which will not be run together. Switching on and off stresses the HV bus bar and can cause voltage and frequency problems.
In a new approach to solar and low voltage (12V & 24V) for lights and ship systems, the solar first charges a separate battery, backed up by a 240VAC charger from the main bus, and excess energy will be DC/DC converted to charge the main system. The solar system is so large compared to the low voltage system that these batteries will be topped off early most mornings however, this design eliminates several inverters.
Whio II proposes to use water for motion damping and increased amenity value. Large commercial systems are more reliable but require three phases power, so separate inverters might be required. Until final weights and performance data is calculated, this issues remains under consideration.
Voltages on board Whio II are 750VDC, 400VAC, 240VAC, 24VDC, and 12VDC. Higher voltages lower heat loading and aren’t more dangerous than fuel, CNG, or hydrogen if installed correctly and safety procedures well defined. We will utilise the industry’s best practice to ensure power sources are isolated and able to be locked out. In an emergency, the 24VDC system will operate all essential ship systems. Once installed, there will be very little to maintain and alter in the course of normal use.
A very big thank you to our electrical engineering partner 3IS for taking on this project and really stepping out of their comfort zone to create something special.