201233046 六、發明說明： 【發明所屬之技術領域】 本發明係有關一種控制裝置，特別是關於一種馬達控制裝置。 【先前技術】 現今控制馬達之技術已臻成熟，習知技藝早已有利用電路來控 制馬達進行旋轉運動的技術，不僅如此，更可藉以利用此電路來改 變馬達轉速、轉向及扭力。201233046 VI. Description of the Invention: [Technical Field] The present invention relates to a control device, and more particularly to a motor control device. [Prior Art] Nowadays, the technology for controlling a motor has matured. The prior art has already used a circuit to control the rotation motion of the motor. Moreover, the circuit can be used to change the motor speed, steering and torque.
現以二相直流無刷馬達為例介紹習知的馬達控制技術。如第j 圖所示，目則習知的馬達控制電路大抵由一相位控制單元I?及三 相位切換開關組14、16、18所組成，其中相位控制單元a係產生 順序f脈寬調變信號（PWM信號）至三相位切換開關組14、16'、18, 而後三相仙換開敝14、16、18會依序將驅動電流輸入至一馬 達20的線圈組中，並使線圈組隨馬達轉子的位置切換電流方向而 產生磁力作為馬達20的輸出扭力。 習知的馬達控制電路是以儲電器22直接作為馬達2〇的能量來 源’而以_來調變電流的大小，因而造成馬達2Q内電流切換頻 仍丄電磁干擾嚴重。再者，由於儲電器22之電壓固定，當馬達2〇 於高速轉動時，感應電動勢增加，因此可輸人至馬達2Q之電流減 少，致使扭力下降，轉速及可載重之負載均受到限制。 習知的煞車回充技術存在·電流大小不—致的問題。 =面速時，感應電動勢高，則回收電流大，在低速時，感應電動 敏回收電流小。此造成-不穩定之煞車阻力，亦令低速段之 …、皁flb；!：回收較無效率。 以組^，本發明係在針對上述之峨，提出達控制裝置， 以解決習知所產生的問題。 鄕里 【發明内容】 容預要目的，在於提供一種馬達控制裝置，其係利用電 使之供應霞，姑料狀她咖域供給馬達 匕電壓將以一量高於馬達之感應電動勢，此電壓差量可提供 201233046 ί ί之電流予馬達以負荷所欲之轉速及負載。因此免除習知馬達 &波寬度調變（隱）控制之需求而減少電磁干擾。當電容之電壓 達感應鶴勢差量越大，灌人馬達之電流越大，縣能施予馬 運較大之扭力以推動較大之負載或進行瞬間之加速。 達上ί目的，本發明提供一種馬達控制裝置，其係連接一馬 ^-儲電n ’馬達具有複數相位，且儲電器連接至儲電地端，馬 j控制裝置包含一第一開關，其係連接儲電器，另有一電感，其具 二Ξ"~、第二端’第—端連接第一開關與—第二開關之一端，第^ 二母之，一端則連接儲電地端。電感之第二端連接一第三開關之一 第—開關之另一端連接馬達地端。還有一第四開關，其具一第 ^第四端’第二端連接電感之第二端與第三開關，第四端連接一 電容之一端，電容之另一端則連接馬達地端。馬達、電容、第四開 ，之第四端與馬達地端連接複數相位_組，其係分別控制通過每 :相位之電流。第-、第二、第三、第四開關皆連接一主控制單元， 3運轉時’主控制單元控制第―、第二、第三、第四開關之導 =狀H儲電n利用上綱關及她關組提供—運轉輸出電流 '•、°馬達，並於電容上產生一高於馬達之感應電動勢的運轉電壓，以 供應馬達提供扭力’且扭力需求越高時電壓差越高。 此外，在煞車作動時，馬達亦可反向運作為一發電機。此時利 用主控制單士控制第-、第二、第三、第四開關之導通狀態，可依 馬達之轉速高低，對感應電動勢作降壓或昇壓㈣充電力至儲電 器。 、兹為使貴審查委員對本發明之結構特徵及所達成之功效更 ，進一步之瞭解與認識，謹佐以較佳之實施例圖及配合詳細之說 明’說明如後： 【實施方式】 以下請同時參閱第2圖，並敘述於馬達運轉時會用到的各元 ，。本發明之馬達控制裝置，連接一馬達24與一儲電器％，儲電 器26連接至儲電地端’馬達24 |有複數相位，在此以三相位為例。 此馬達控繼置包含-她控鮮元28與複數她開關組，為了 201233046 位相位開關組之數量亦以三為例，即相位開關組30、 開關組32、包^立開，3〇包含第一、第二子開關36、38 ;相ί H 弟第四子開關40、42 ;相位開關組34包含第A two-phase DC brushless motor is taken as an example to introduce a conventional motor control technique. As shown in the figure j, the conventional motor control circuit is generally composed of a phase control unit I? and a three-phase switching switch group 14, 16, 18, wherein the phase control unit a generates a sequence f pulse width modulation. The signal (PWM signal) is connected to the three-phase switching switch group 14, 16', 18, and then the three-phase switching switch 14, 16, 18 sequentially inputs the driving current into the coil group of a motor 20, and the coil group is A magnetic force is generated as the output torque of the motor 20 by switching the direction of the current with the position of the motor rotor. The conventional motor control circuit uses the energy storage device 22 as the energy source of the motor 2 而 to modulate the current by _, thereby causing the current switching frequency in the motor 2Q to be severe. Furthermore, since the voltage of the accumulator 22 is fixed, when the motor 2 is rotated at a high speed, the induced electromotive force is increased, so that the current that can be input to the motor 2Q is reduced, so that the torque is lowered, and the load of the rotational speed and the load can be limited. The conventional brake recharge technology exists and the current is not the same. = When the surface speed is high, the induced electromotive force is high, and the recovery current is large. At low speed, the induced electro-sensitive recovery current is small. This causes - unstable braking resistance, and also makes the low speed section ..., soap flb;!: recycling is less efficient. In view of the above, the present invention proposes a control device to solve the problems caused by the prior art.鄕里【Abstract 】 The purpose of the present invention is to provide a motor control device that utilizes electric power to supply the Xia, and that the voltage supplied to the motor 匕 will be higher than the induced electromotive force of the motor. The difference provides the current of 201233046 ί ί to the motor to load the desired speed and load. This eliminates the need for conventional motor & wave width modulation (implicit) control to reduce electromagnetic interference. When the voltage of the capacitor reaches the difference of the induced crane potential, the larger the current of the filling motor, the county can give the horse a larger torque to drive a larger load or accelerate instantaneously. For the purpose of the present invention, the present invention provides a motor control device that is connected to a motor, the motor has a plurality of phases, and the storage device is connected to the storage ground, and the control device includes a first switch. The utility model is connected to the storage device, and has an inductor, which has a second axis "~, the second end of the second end is connected to the first switch and the second switch, and the second end is connected to the storage end. The second end of the inductor is connected to one of the third switches. The other end of the switch is connected to the ground end of the motor. There is also a fourth switch having a fourth end end connected to the second end of the inductor and a third switch, the fourth end being connected to one end of the capacitor, and the other end of the capacitor being connected to the ground end of the motor. The fourth end of the motor, the capacitor, and the fourth open are connected to the ground end of the motor by a plurality of phase groups, which respectively control the current through each phase. The first, second, third, and fourth switches are all connected to a main control unit. When the 3 is in operation, the main control unit controls the conduction of the first, second, third, and fourth switches. Off and her off-supplied - run the output current '•, ° motor, and generate a running voltage higher than the motor's induced electromotive force on the capacitor to supply the motor to provide torque' and the higher the torque demand, the higher the voltage difference. In addition, the motor can also operate in reverse as a generator when the brake is actuated. At this time, the main control unit is used to control the conduction states of the first, second, third, and fourth switches, and the induced electromotive force can be stepped down or boosted (4) to the storage device according to the rotation speed of the motor. Further understanding and understanding of the structural features and the achievable effects of the present invention will be provided by the preferred embodiment and the detailed description of the invention as follows: [Embodiment] Refer to Figure 2 and describe the elements that will be used when the motor is running. The motor control device of the present invention is connected to a motor 24 and a storage device %, and the storage battery 26 is connected to the storage terminal "motor 24" having a complex phase, here taking three phases as an example. The motor control relay includes - her control element 28 and a plurality of her switch groups. For the number of 201233046 bit phase switch groups, the number is also three, that is, the phase switch group 30, the switch group 32, the package is open, and the third switch includes First and second sub-switches 36, 38; phase H H fourth sub-switches 40, 42; phase switch group 34 includes
開關44、46。相位控制單元28接收馬達24輸出之霍 fX控制子開關36、38、4G、42、44、46。為了使馬達 4Π、49 μ目位控制單^ 28係以下列順序進行控制子開㈣36、38、 览一 、、46週期作動：首先，霍爾U，V，f之準位為1，〇，1時， ^了仙子_ 36、42導通，第二、第三、第五、第六子開關 +門ωπ44、46皆關閉；接著，霍爾U，V，W2準位為仫0，0時， u 、46導通’子開關38、38、42、44皆關閉；第三，霍爾 川\之準位為丨，丨，〇時’子開關40、46導通，子開關36、38、 狀道4皆關閉；第四，霍爾U，V，W之準位為0，1，0時，子開關4〇、 導通，子開關36、42、44、46皆關閉；第五，霍爾u，V，W之準 位為0’；1，1時，子開關44、38導通，子開關36、40、42、46皆關 閉，最後，霍爾U，V，W之準位為〇, 〇, 1時，子開關44、42導通， 子開關36、38、40、祁Μ閉。 馬達24運轉時各相位線圈將因其位置及轉速而產生大小不同 之感應電動勢。當轉速較低時，此感應電動勢低，當轉速較高時， =應電動勢高。本發明將對f絲料等之電壓，此電壓將以-量咼於馬達24之感應電動勢，此電壓差量將決定於馬達之轉速及 負載，以免除習知馬達脈波寬度調變（PWM)控制之需求而減少電 磁干擾。當差量越大，灌入馬達24之電流越大，則將能施予馬達 24較大之扭力以推動較大之負載或進行瞬間之加速。 j發明更包含一第一開關48與一電感50，第一開關48連接 儲電器26，電感5〇具一第一、第二端，且第一端連接第—開關48 與一第二開關52之一端，第二開關52之另一端則連接儲電地端。 電感50之第二端連接一第三開關54之一端，第三開關54之另一 端則連接至馬達地端。另有一第四開關56,其具一第三、第四端， 第三端連接電感50之第二端與第三開關54’第四端連接—電容58 之一端，電容58另一端則連接馬達地端。相位開關組3〇、32、34 201233046 更連接馬達24、電容58與馬達地端，以分別控制通過每一相位之 電/瓜。上述第一、第二、第三、第四開關48、π、54、56皆連接 一主控制單元60，在馬達24運轉時，主控制單元60係控制第一、 第一、第二、第四開關48、52、54、56之導通狀態，則儲電器26 利用上述開關48、52、54、56及相位開關組3〇、32、34提供一運 轉輸出電流給馬達24，並於電容58上產生-高於馬達24之感應 電動勢的運轉電壓，以供應馬達24提供扭力，且扭力需求越高時 電壓差越高。 虽馬達24在低速運轉而使產生之感應電動勢小於儲電器邡之 電壓時，主控制單元6〇係先於第一時段控制第一、第四開關48、 • 56導通’第二、第三開關52、54關閉，此時電流開始上升。再於 第一時段控制第二、第四開關52、56導通，第一、第三開關48、 54關閉’此時電流開始下降。如此便可提供該運轉輸出電流，並 於電谷58上產生運轉電壓。經由控制第一時段及第二時段之長 度’可使電流維持在某-區間，間接使電容58之碰及流入馬達 24之，"IL维持在某一區間以產生適量之扭力以維持負載及轉速。 當馬達24在高速運轉而使產生之感應電動勢高於儲電器26之 電屋時’主控制單兀60係先於第一時段控制第―、第三開關48、 54導通，第二、第四_ 52、56關閉，此時電流開始上升並儲能 • 於電感中。再於第二時段控制第一、第四開關48、％導通，第 -、第二開關52、54 _ ’此時電流轉而流人電容58及馬達24， 並開始下降。如此便可提供上述之運轉輸出電流，並於電容58上 f生運轉電壓。經由控制第—時段及第二時段之長度，可使電流維 ，在某-區間，間接使電容58之電壓及流人馬達24之電流維持在 某一區間而使馬達24維持於高速運作。 根據上面所述’當馬達24運作時，皆必須設定二時段之開關 =換’，此’主控制單元6〇更連接—第—電流綱器招，第一電 机制益62連接儲電地端與馬達地端，並預設一第一電流值，且 f-電阻64之二端分別連接儲電地端與馬達地端。第一電流_ 益62係利用電阻64偵測儲電器26產生之儲電電流 ，當因第一時 201233046 段過長或因負鑛化，而導賴電電流超過第―電流值時，第一電 ^偵^器60通知主控制單元6〇主動結束第一時段之操作，並啟動 ==壞如此亦可使儲電器26之供應電流小於其最大供 在煞車作動時，馬達24可以反向運作為一發電機，提供一獨 =之能量·路徑’此路徑可提供穩定的電細充機制予儲電器 此，而使能量有效率的回收。 當煞車作動於高速運轉時，主控鮮元⑽進人高速煞車模 t馬達24之感應電動勢高於儲電11 26之電壓。因此馬達24與 Ilf之間財—適當之降龜以避免職之懸使電流持續 =而J過電路系統及儲電器26自身之負荷。主控制單元6〇控制 此t 4四開關48、52、54、56之導通狀態以達成 6/ 一降壓器之運作分為二個時段。主控制單元 H 控制第一、第四開關48、56導通，第二、第三開 2"6。接^至關ί，此時流出馬達24之電流開始上升並流入儲電器 笛妾者再於第二時段控制第一、第三開關48、54導通，第二、 ίΠ t Γ醜，此日_開始下降。如此便可驅動馬達％ ^二煞車輸出電流給儲電器26。經由控制第—時段及第二時段 錢轉在某—邮，使馬㈣獲得 式。動於錢運轉時，主控解元6G進人低速煞車模 儲電，t感應電動勢低於儲電器26之電壓。因此馬達24與 26之間須有-適當之升壓器 電=!；主控制科6Q控制第―、第二=二= 器之驚u -6之導通狀如達成此—升壓11之魏。此一升壓 第四夺段。主控制單元60先於第一日夺段控制第一、 ί 2=電t '第糊52、54關閉，此時流出馬 日ίίL導通’第一、第三開關48、54關閉，此 于L始下降L儲㈣26。如此便可驅動馬達24提供一煞 201233046 車=電流給儲電器26。經由控制第一時段及第二時段之長产， 声而H之電流維持在某—區間’使馬達24獲得一穩ΐ之 ”、、車與加速馬;^ 24運作情況相同，由於必須設定二時 、===單元6〇更連接一第二電流娜6: ί二‘ 一電机偵測器66係利用電阻64 γ貞測馬達2 電流，在煞車電流超過第二電流值時，第車 以避免損壞儲電器。故德作，並啟動第二時段之操作， ^讓主控制單元6〇判斷進行高 -電壓偵測器' 68,其偏技*快生ηΛ 早摸式更设有 並預設一偵測電壓，此偵测電^為ίίϋ 26^^2。6^^：58， 電動勢並非一穩定之直棘壓，其將隨 轉’迷g =7_時，偵測器68偵測電容58之iiS 測電壓比較，以判斷馬達24 心电魘亚興偵 壓高於伯測電麗時，主控制單同古。·在電容58之兩端電 繼蝴物1彳酬， 造、特徵及精神所為之均等變化與圍所述之形狀、構 專利範圍内。 與丨，飾，均應包括於本發明之申請 【圖式簡單說明】 第第先ί技術之馬達控制電路之電路示意圖。 =2圖為本發明之裝置電路示意圖。 【主要元件符號說明】 12相位控制單元 16相位切換開關、组 =開關組 20馬達 18相位切換開關組 22儲電器 201233046 24 馬達 26 儲電器 28 相位控制單元 30 相位開關組 32 相位開關組 34 相位開關組 36 第一子開關 38 第二子開關 40 第三子開關 42 第四子開關 44 第五子開關 46 第六子開關 48 第一開關 50 電感 52 第二開關 54 第三開關 56 第四開關 58 電容 60 主控制單元 62 第一電流偵測器 64 電阻 66 第二電流偵測器 68 電壓偵測器Switches 44, 46. The phase control unit 28 receives the HX control sub-switches 36, 38, 4G, 42, 44, 46 of the motor 24 output. In order to make the motor 4Π, 49 μ目 position control unit 28 control in the following order (four) 36, 38, one, and 46 cycles: First, the position of Hall U, V, f is 1, 〇, 1 o'clock, ^ Fairy _ 36, 42 conduction, second, third, fifth, sixth sub-switch + door ωπ44, 46 are closed; then, Hall U, V, W2 level is 仫 0, 0 , u , 46 conduction 'sub-switches 38 , 38 , 42 , 44 are all closed ; third , the threshold of Hallchuan \ is 丨 , 丨 , 〇 ' sub-switches 40 , 46 conduction , sub-switches 36 , 38 , 4 Fourthly, when the positions of Hall U, V, and W are 0, 1, 0, the sub-switches 4〇, turn-on, and the sub-switches 36, 42, 44, 46 are all turned off; fifth, Hall u, V, W is 0'; when 1,1, sub-switches 44, 38 are turned on, sub-switches 36, 40, 42, 46 are turned off, and finally, the positions of Hall U, V, W are 〇, 〇 At 1 o'clock, the sub-switches 44, 42 are turned on, and the sub-switches 36, 38, 40 are turned off. When the motor 24 is in operation, each phase coil will generate an induced electromotive force of a different magnitude depending on its position and rotational speed. When the rotational speed is low, the induced electromotive force is low, and when the rotational speed is high, the electric potential is high. The present invention will apply voltage to the f-wire or the like, and this voltage will be proportional to the induced electromotive force of the motor 24. The voltage difference will be determined by the motor speed and load to avoid the conventional motor pulse width modulation (PWM). ) Control the demand to reduce electromagnetic interference. When the difference is larger, the greater the current injected into the motor 24, the greater the torque of the motor 24 can be applied to drive a larger load or to accelerate instantaneously. The invention further includes a first switch 48 and an inductor 50. The first switch 48 is connected to the storage device 26. The inductor 5 has a first end and a second end, and the first end is connected to the first switch 48 and the second switch 52. At one end, the other end of the second switch 52 is connected to the storage ground. The second end of the inductor 50 is connected to one end of a third switch 54, and the other end of the third switch 54 is connected to the ground end of the motor. There is a fourth switch 56 having a third end and a fourth end. The second end of the third end connecting inductor 50 is connected to the fourth end of the third switch 54'. One end of the capacitor 58 is connected to the other end of the capacitor 58. Ground. The phase switch group 3〇, 32, 34 201233046 is further connected to the motor 24, the capacitor 58 and the motor ground to respectively control the electric/gull passing through each phase. The first, second, third, and fourth switches 48, π, 54, and 56 are all connected to a main control unit 60. When the motor 24 is in operation, the main control unit 60 controls the first, first, second, and second When the four switches 48, 52, 54, 56 are in the on state, the storage device 26 provides an operating output current to the motor 24 by using the switches 48, 52, 54, 56 and the phase switch groups 3, 32, 34, and the capacitor 58 An operating voltage is generated above the induced electromotive force of the motor 24 to supply the torque provided by the motor 24, and the higher the torque demand, the higher the voltage difference. Although the motor 24 is operated at a low speed so that the induced electromotive force generated is less than the voltage of the accumulator, the main control unit 6 controls the first and fourth switches 48, • 56 to conduct the second and third switches prior to the first time period. 52, 54 is turned off, and the current starts to rise. The second and fourth switches 52, 56 are again turned on during the first period, and the first and third switches 48, 54 are turned off. At this time, the current begins to drop. This provides the operational output current and produces an operating voltage across the valley 58. By controlling the length of the first time period and the second time period, the current can be maintained in a certain interval, indirectly causing the capacitance 58 to hit and flow into the motor 24, "IL is maintained in a certain interval to generate an appropriate amount of torque to maintain the load and Rotating speed. When the motor 24 is running at a high speed so that the induced electromotive force generated is higher than that of the electric storage device 26, the main control unit 60 is controlled by the first and third switches 48, 54 before the first time period, second and fourth. _ 52, 56 is off, at which point the current begins to rise and the energy is stored in the inductor. Then, the first and fourth switches 48 and % are turned on in the second period, and the first and second switches 52, 54 _ ' at this time, the current flows to the capacitor 58 and the motor 24, and starts to fall. In this way, the above-mentioned operating output current can be supplied, and the operating voltage can be generated on the capacitor 58. By controlling the length of the first period and the second period, the current can be maintained, and in a certain interval, the voltage of the capacitor 58 and the current of the flow motor 24 are indirectly maintained in a certain interval to maintain the motor 24 at a high speed. According to the above, when the motor 24 is operated, it is necessary to set the switch of the second time period = change, and the main control unit 6 is connected to the first-current device, and the first electrical mechanism is connected to the storage ground. And the motor ground end, and a first current value is preset, and the two ends of the f-resistor 64 are respectively connected to the storage ground end and the motor ground end. The first current _ 益 62 is used to detect the stored current generated by the storage device 26 by using the resistor 64. When the first period 201233046 is too long or due to negative mineralization, and the current is exceeded by the first current value, the first The motor controller 60 notifies the main control unit 6 to actively end the operation of the first time period, and starts == bad, so that the supply current of the storage device 26 can be made smaller than its maximum for the brake operation, the motor 24 can operate in reverse. For a generator, provide a unique energy path. This path can provide a stable electric charging mechanism to the storage device, so that energy can be efficiently recovered. When the brake is actuated at high speed, the main control fresh element (10) enters the high-speed brake mode. The induced electromotive force of the motor 24 is higher than the voltage of the stored electricity 11 26 . Therefore, between the motor 24 and the Ilf - the appropriate to reduce the turtle to avoid the current suspension current = and J through the circuit system and the storage device 26 itself. The main control unit 6 controls the conduction state of the four switches 48, 52, 54, 56 to divide the operation of the 6/one bucker into two periods. The main control unit H controls the first and fourth switches 48, 56 to be turned on, and the second and third switches 2 " Connect to ^, when the current flowing out of the motor 24 begins to rise and flows into the storage device, the second and third switches 48, 54 are turned on during the second period, and the second, ίΠt Γ ugly, this day _ begin descending. In this way, the motor %^2 car output current can be driven to the storage device 26. By controlling the first period and the second period, the money is transferred to a certain post, so that the horse (four) is obtained. When the money is running, the main control solution 6G enters the low-speed brake mode to store electricity, and the induced electromotive force is lower than the voltage of the storage device 26. Therefore, between the motors 24 and 26, there must be - appropriate booster power =!; the main control section 6Q controls the first - second = two = the stun of the ue -6 to achieve this - the boost 11 Wei . This boost is the fourth to win. The main control unit 60 controls the first, ί 2 = electric t 'the second paste 52, 54 is turned off before the first day, and the flow out of the horse ίίL turns on the first and third switches 48, 54 are closed, which is L Start falling L storage (four) 26. In this way, the motor 24 can be driven to provide a 煞201233046 car=current to the accumulator 26. By controlling the long-term production of the first time period and the second time period, the current of the sound and H is maintained at a certain interval - the motor 24 is obtained stably, and the vehicle and the acceleration horse are operated in the same manner; Time, === unit 6〇 is connected to a second current Na 6: ί二' A motor detector 66 uses the resistance 64 γ to measure the motor 2 current, when the brake current exceeds the second current value, the first car In order to avoid damage to the electrical storage device, the operation is started, and the operation of the second time period is started. ^ The main control unit 6 determines that the high-voltage detector is 68, and its partial technique is fast. Preset a detection voltage, this detection power is ίίϋ 26^^2. 6^^:58, the electromotive force is not a stable straight ratchet, it will follow the turn '迷 g = 7_, the detector 68 Detecting the voltage of the iiS of the capacitor 58 to determine the motor 24, the power of the Yaxing is higher than that of the Boss, and the main control is the same as the ancient one. The changes in creation, characteristics and spirit are within the scope of the above-mentioned shapes and structures. The design and application of the invention shall be included in the application of the invention. Brief description of the circuit] The circuit diagram of the motor control circuit of the first technology. Fig. 2 is a schematic diagram of the circuit of the device of the present invention. [Description of main components] 12 phase control unit 16 phase switching switch, group = switch group 20 motor 18 Phase change switch group 22 storage device 201233046 24 motor 26 storage device 28 phase control unit 30 phase switch group 32 phase switch group 34 phase switch group 36 first sub switch 38 second sub switch 40 third sub switch 42 fourth sub switch 44 Fifth sub-switch 46 sixth sub-switch 48 first switch 50 inductor 52 second switch 54 third switch 56 fourth switch 58 capacitor 60 main control unit 62 first current detector 64 resistor 66 second current detector 68 Voltage detector