Hitachi AN091802-1 Connection method, Powering Inverters from DC, DC supply connection methods

Powering Inverters from DC

It is possible to power inverters from a DC Power source, or to connect the DC Bus of multiple inverters together to achieve energy savings, since inverters in power driving mode can use power from those that are in regeneration mode.

[1] Connection method

There are several ways for DC bus connection of the inverters. (Examples of 3-phase 200V or 400V class inverter.)

Case 1 : Connected in parallel to a common DC bus Case 2 : Connected in parallel to an A-fed inverter

DC power	AC power
supply	supply
	INV #1
	M 1
	INV #2

+INV #1

-

INV #2

M 1

M 2

M 2

INV #n

INV #n

M n

M n

Case 3 : AC & DC Connected together

AC power supply

+ INV #1

-

INV #2

	DC supply connection methods
	+	INV
M 1		M
	-

ŒConnecting to + and - terminal

M 2

INV #n

M n

+	INV
	M
-

•Connecting to AC inputs and - terminal

ØAdvantage and disadvantages of each connection method.

Item	Contents		Advantage	Disadvantage
Œ	Connecting to + & - terminal	Ÿ	No concern for the	Ÿ There will be no inrush
			rectifier bridge diodes.	current limiting.
•	Connecting to AC inputs and - terminal	Ÿ	Integrated inrush current	Ÿ Rectifier bridge diodes
			limiting circuit is used.	of the main inverter may
				need to be up-sized.