程式化永磁馬達設計概念 by python

Why use program to design motor

Save labor cost - program 具有自動化的好處，重複的步驟只要編寫一次，之後只需要執行程式就好
Code represent design concept and step - 當設計變成code，並且利用的是好理解且通用的 code structure ，人員轉換造成的工作問題就會下降，因為所有人只要能看懂code，就能看懂設計步驟，進而理解設計。

How to represent motor design concept and step

專注在兩個非常重要卻又簡單的東西 data & function。

Input & Output Data

先思考 input 與 ouput的data是什麼

input data - 規格
output data - 定子外徑、馬達長度、匝數、BEMP(@1000rpm)、操作點數據(torque data, average torque, speed, torque ripple, current, current density, line voltage, coreloss, copperloss)

Design function and data

手算一次將規格轉換成 馬達模型數據 與 電氣數據。
將中間所有的步驟，以及當中用到的 數據名稱 記錄下來。
將 數據名稱 根據步驟的概念分類 (定轉子、磁石、電氣…等)。使用 dict 這個 data structure將其收起來，還不知道的值就先給 None，用專案中馬達設計的部分呈現如下。

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64


motor_cal_params = {
    "stator": {
        "OD_limit": None,
        "slot": 12,
        "shoes_height_front": 1,
        "shoes_height_back": 1,
        "slot_open": 4.5,
        "slot_corner_arc": 0.5,
    },
    "rotor": {
        "pole": 10,
        "mag_emb": 0.8,  # easier magetization
    },
    "coil": {
        "conductor_OD": 1,
        "y_para": 1,
        "membrane_ratio": 1.075,
        "slot_fill_factor": 0.43,
    },
    "estimate": {
        "kt_ke_ratio": 0.9,
        "max_J": 18,
        "voltage_buffer": 0.9,
        "torque_density":   25,
        "teeth_mag_ang_ratio": 0.6,
        "york_teeth_ratio": 0.7,
        "rotor_OD_ratio": 0.6,
        "bg": 1.2,
        "mag_pc": 7.5,  # for not easy to broke
    },
    "calculation": {
        "est_rotor_OD": None,
        "est_stator_OD": None,
        "mag_thick": None,
        "teeth_width": None,
        "york_width": None,
        "slot_height": None,
        "slot_width_front": None,
        "slot_width_back": None,
        "para_conductor": None,
        "coil_turns": None,
        "real_slot_fill_factor": None,
    },
    "material": {
        "stator": "\"35CS250_steel\"",
        "rotor": "\"35CS250_steel\"",
        "magnet": "\"N44SH_20deg_mag\"",
        "coil": "\"copper\"",
    },
    "setting": {
        "cycle": 1,
        "split_step": 50
    },
    "voltage_dc": None,
    "length": None,
    "airgap": 0.5,
    "w_factor_10p12s": 0.933,
    "ke":               None,
    "kt":               None,
    "corner_speed_rpm": None,
    "max_speed_rpm":    None,
    "max_current_rms":  None,
    "core_loss_factor": 1,
}

將步驟拆成小的function，專案中馬達設計的部分如下

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24


def ktke_calculation(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params
def assign_spec_value(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params
def expend_NBLR(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params
def expend_stator_teeth_york(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params
def expend_stator_slot(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params
def expend_magnet(total_cal_params):
    # 計算 total_cal_params 的某個值 [calculating some value of total_cal_params dict]
    # 將 計算值 替算掉原本在total_cal_params中的未定值 [Replace the dict value by calculated results]
    return total_cal_params

將 3. 的數值dict貫穿 4. 的所有function (3.的 motor_cal_params 放在 ctx[params]中)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10


total_cal_params = ctx["params"]

ktke_calculation(total_cal_params) and \
    assign_spec_value(total_cal_params) and \
    expend_NBLR(total_cal_params) and \
    expend_stator_teeth_york(total_cal_params) and \
    expend_stator_slot(total_cal_params) and \
    expend_magnet(total_cal_params)

    print(total_cal_params)

Ansys maxwell 的溝通部分也是用同樣的方式，可參考這裡

Conclusion

使用上述的方法，是不是很單純，且很直觀就能看懂設計的過程，debug也非常容易，執行程式時將total_cal_params 印出來看就好。

當整個程式設計完成後，接下來就是去優化每一個 function & data 讓它們更容易被看懂，更能直觀的對應馬達設計。

更詳細可參考我的設計，未來還會持續的優化設計。