Variable frequency drive systems for hydraulic elevators –
an overview

Driven by this global discussion about energy efficiency, some providers of hydraulic drives have tackled this issue by bringing variable frequency drives into their product range. These are presented as the perfect solution to the energy-conscious customer.
Taking a closer look, the technically literate and critical observer will notice considerable differences between the various offerings. This article is designed to help the interested reader to differentiate between the various types of energy efficient hydraulic drives.

Content:

An overview

• Do we need variable frequency drive at all?

The different types of variable frequency drives

• Conventional up and down ride
• Frequency drive controlled up ride
• Load-dependent speed reduction / limited power connection
• Frequency drive controlled down ride
• Frequency drive controlled down ride with recovery

Reasons for using variable frequency drive with hydraulic power units

• Number of travels: High ride frequency
• Energy efficiency
• Load-dependent speed reduction / current limiter

Summary