Another thing that's not well documented is that (as of PHP 7.0/7.1) pg_convert doesn't like non-scalar types and will fail (but not throw just emit an E_WARNING and return false) if you pass it anything other than a string or a number, including an array or something like a DateTime. If you want to insert those types, you actually have to convert those yourself.

Also, somewhat surprisingly, $table_name is not compatible with the output of pg_​escape_​identifier, or seemingly any other kind of escaping.