H Bridge

Example: how to make an H Bridge for a reversing VDC motor application or alternative energy applications:

First you make an H bridge with 4 Power-io units. Power-io terminals 1 and 2 = the power terminals for the motor connections.

Use a HDD product where the voltage rating is at least twice the motor's rating. For example: a HDD-06V75 is rated for 60 volts DC so it would be a good choice for a 12 volt or 24 volt motor. Determine the maximum amperage inrush required for the motor and make sure that it is with-in the capability of the Power-io unit. The HDD-06V75 is rated for 75 amps when on a properly sized heat sink.
H Bridge

When the motor (inductive load) is turned off, there is a large voltage surge. You can not use a diode to suppress this due to reversing polarity of the installation. Therefore, use an MOV across the motor. One supplier of MOVs is: littelfuse.com

For example, if using a 12 or 24 VDC motor, the MOV should 1) be rated higher than the load, 2) have a clamping voltage approximately equal or lower than the Power-io solid state relay rating, and 3) be a large disk size. For this example, part number V36ZA70 or V36ZA80 might be a good choice. The exact part number should be selected by your engineering department.

MOV selection
H Bridge

The control inputs are wired as shown. The inputs can be generated from a PLC, other controller, or a three position switch. The three states are: clockwise, counter clockwise, and no input. It is important to permit the motor to come to a stop before reversing direction.

H Bridges are used with reversible VDC motors, VDC linear positioning actuators, some charging/discharging battery applications, some solar cell applications, solar cell positioning systems, and more.

Caution: if you turn ON all of the relays at the same time, you will short out your power supply and you will damage the solid state relays. Only turn ON the pair for clockwise rotation or for counter clockwise rotation.

The above information is a description of an H Bridge concept. Your installation may have additional considerations that are not discussed here. Return to the DC switching solid state relay page (HDD Family)