1:用蓝牙工具测试是否是硬件问题，我用lightBlue测试硬件是没问题的
2:那就是我的问题了，最后解决如下：需再外部断开的回调中，重新初始化蓝牙设备管理对象，重新启动搜索就可以搜索到该设备了

//Peripherals断开连接
- (void)centralManager:(CBCentralManager *)central didDisconnectPeripheral:(CBPeripheral *)peripheral error:(NSError *)error{
    NSLog(@">>>外设连接断开连接 %@: %@___需要连接的设备:%@__来自外部断开:%d", [peripheral name], [error localizedDescription],[self.needReConnectPeripheral name],isFromReconnect);
    //清除当前连接
    [self removeDisconnectPeripheral:peripheral];
    
    if(isFromReconnect){//来自重连前的断开
        isFromReconnect = NO;
        if(self.needReConnectPeripheral){
            self.peripheral = self.needReConnectPeripheral;
            [manager connectPeripheral:self.peripheral options:nil];
        }
    }else{//来自外部断开
        //清除所有重新开始
        [self.peripheralArray removeAllObjects];
        //初始化并设置委托和线程队列，最好一个线程的参数可以为nil，默认会就main线程
        manager = [[CBCentralManager alloc] initWithDelegate:self queue:dispatch_get_main_queue()];
        [manager scanForPeripheralsWithServices:nil options:0];
    }

}