Here a small JS code to paste in the console to see who upvote/downote your own post.

openerp.website.session.session_reload().then(function() { 
     var my_user = openerp.website.session.uid  
                   || parseInt($('.website_forum .navbar a[href^="/forum/help-1/user/"]').attr('href').split('/').pop());
     openerp.jsonRpc('/web/dataset/call_kw', 'call', {
         model: 'forum.post.vote',
         method: 'search_read',
         args: [[['recipient_id','=',my_user]], ['post_id', 'vote', 'user_id']],
         kwargs: { context: openerp.website.get_context()}
     }).then(function(results) { 
         _.each(results, function(result) { 
           console.log('Post: ' + result.post_id[0] + ' | ' + result.vote + " by " + result.user_id[1])     });
     })
})

Or to know on One post, who downvote / upvote ...

var post = <THE_POST_ID_HERE>;
openerp.jsonRpc('/web/dataset/call_kw', 'call', {
   model: 'forum.post.vote',
   method: 'search_read',
   args: [[['post_id','=',post]], ['user_id', 'vote']],
   kwargs: { context: openerp.website.get_context()}
}).then(function(result) { 
   function vote(x) { 
     this.user_name = x.user_id[1];
     this.user_id = x.user_id[0];
     this.vote = parseInt(x.vote);
   }
   res = [];
   _.forEach(result, function(x){ res.push(new vote(x)); }); 
   console.table(res, ['vote','user_id','user_name']);
})