tensorflow kears转pb

        model = tf.keras.models.Model()
        function = _saving_utils.trace_model_call(model)
        concrete_func = function.get_concrete_function()
        frozen_func = convert_variables_to_constants_v2(
            concrete_func, lower_control_flow=False)
        input_shape = {"input_1" : [1，640，640，3]}
        _set_tensor_shapes(frozen_func.inputs, input_shape)
        frozen_func.graph.as_graph_def()
        tf.io.write_graph(graph_or_graph_def=frozen_func.graph,
                        logdir="./frozen_models",
                        name="model.pb",
                        as_text=False)