php7 数据导出Excel office 2011中文乱码问题

public function test()
{
    $data = array(
        array(
            'name' => '对对对',
            'score' => 80,
            'grade' => '急急急'
        ),
        array(
            'name' => '嗯嗯嗯',
            'score' => 70,
            'grade' => '黑乎乎'
        ),
        array(
            'name' => '正在',
            'score' => 80,
            'grade' => '也一样'
        ),
        array(
            'name' => '啊啊啊',
            'score' => 203,
            'grade' => '日日日'
        )
    );

    $titleList = array('姓名', '总分', '等级');
    $fileName = '高三(3)班 7 月份考试结果';

    //ini_set("max_execution_time", "3600");
    $csvData = '';

    // 标题
    $nums = count($titleList);
    for ($i = 0; $i < $nums - 1; $i++) {
        $csvData .= '"' . $titleList[$i] . '",';
    }
    $csvData .= '"' . $titleList[$nums - 1] . "\"\r\n";

    foreach ($data as $key => $row) {
        $i = 0;
        foreach ($row as $_key => $_val) {
            $_val = str_replace("\"", "\"\"", $_val);
            if ($i < ($nums - 1)) {
                $csvData .= '"' . $_val . '",';
            } elseif ($i == ($nums - 1)) {
                $csvData .= '"' . $_val . "\"\r\n";
            }
            $i++;
        }
        unset($data[$key]);
    }

    $csvData = mb_convert_encoding($csvData, "cp936", "UTF-8");  （这句解决Excel版本低导出乱码问题）
    $fileName = empty($fileName) ? date('Y-m-d-H-i-s', time()) : $fileName;
    $fileName = $fileName . '.csv';
    header("Content-type:text/csv;");
    header("Content-Disposition:attachment;filename=" . $fileName);
    header('Cache-Control:must-revalidate,post-check=0,pre-check=0');
    header('Expires:0');
    header('Pragma:public');
    echo $csvData;
    die();
    
}