100V 50Hz to 120V 60Hz 4kVA frequency converter

[lyseo]

Hi All

I'm looking for a solution to convert from the 100V 50Hz that is used in East Japan to the 120V 60 Hz needed for the landline of a US RV. Minimum 4kVA required. I've spent hours scouring the web for a frequency converter that can do this. Also considering to use a AC/DC and DC/AC combo.

Suggestions?

Thanks,
Øyvind

 

[drcampbell]

I'd start by evaluating whether 120-volt 60-Hz power is actually necessary.

Modern electronics with switch-mode power supplies are insensitive to frequency and most will work just fine on 100 volts.
A 3-way absorption refrigerator is insensitive to frequency and will work at 100 volts. At high ambient temperatures, it might not keep up but it won't suddenly fail.
Induction motors will operate at 5/6 speed and reduced torque. They won't necessarily overheat on the lower voltage because the volts/Hz ratio is the same as what they're designed for.
Brush-type motors will operate on 50 Hz. (or 0 Hz) At 100 volts, they'll provide somewhat less speed & torque.
Anything that runs on 12 volts DC isn't sensitive to the line voltage/frequency.

My big question would be your battery charger and 12-volt converter. If it's an unregulated transformer type, it will deliver 10 volts, which is useless.
Upgrading to a switch-mode charger/converter might be the only adaptation necessary.

 

[Besoeker]

Also considering to use a AC/DC and DC/AC combo.

As far as I'm aware that's how most static frequency converters work. Certainly in the variable frequency drives area. But I'm with the drcampbell fellow. Check that you really need a converter for your application.

 

[zbang]

You may be able to simply install a 20v boost transformer and use 120v 50Hz. It would be surprising if everything in the RV needs both 120v and 60Hz.

 

[jumper]

Japan is interesting. Half the country has a 50 Hz supply and the other half is 60 Hz.

 

[GoldDigger]

You may be able to simply install a 20v boost transformer and use 120v 50Hz. It would be surprising if everything in the RV needs both 120v and 60Hz.

But for some motor loads the combination of 120V and 50Hz might actually overload the motor, as it raises the V/f ratio. A lot depends on what kind of load the motor is driving and how close to saturation the motor was designed to operate.

 

[Besoeker]

Japan is interesting. Half the country has a 50 Hz supply and the other half is 60 Hz.

And they us a DC link to connect them.

 

[jumper]

And they us a DC link to connect them.

I might as well get tutored here and ask why since OP has not responded yet.

Because DC has no frequency and therefore power can transmitted back and forth?

 

[mbrooke]

I might as well get tutored here and ask why since OP has not responded yet.

Because DC has no frequency and therefore power can transmitted back and forth?

Correct. Any frequency can be rectified to DC, and DC can be inverted to any frequency. Hence the DC link between the to systems. Here is a similar but smaller example of HVDC used to interconnect two different frequencies:


https://www.youtube.com/watch?v=ZOTGuWCfS-A

 

[jumper]

Correct. Any frequency can be rectified to DC, and DC can be inverted to any frequency. Hence the DC link between the to systems. ]

I surmised as such, thanks.

 

[drcampbell]

... Because DC has no frequency and therefore power can transmitted back and forth?

Power can also be transmitted back and forth among AC grids, provided they're at the same frequency and synchronized. Because that option isn't available when the two AC grids operate at different frequencies, Japanese engineers opted to convert AC to DC, then back to AC at the other frequency.

 

[mbrooke]

I surmised as such, thanks.

Yup, you did, and spot on

 

[Besoeker]

I might as well get tutored here and ask why since OP has not responded yet.

Because DC has no frequency and therefore power can transmitted back and forth?

It allows conversion from one frequency to another.
Whether it is reversible depends on the circuit topology.

 

[AdrianWint]

It allows conversion from one frequency to another.
Whether it is reversible depends on the circuit topology.

Indeed. Another subtlety is that, with an AC link, the direction of power flow is determined by the laws of physics & loadflow. With a HVDC link the power can be 'forced' to flow in which ever direction its human operators wish, even if that where the opposite to that which loadflow conditions would dictate.

 

[mgookin]

Japan is interesting. Half the country has a 50 Hz supply and the other half is 60 Hz.

Then OP can't be the first guy who needs to solve this problem there.

What does everyone else do?