Control device and electric power steering device that uses this

Abstract

Control device for controlling a motor (80) which is rotated by electrical energy, wherein the control device comprises: an inverter (11) with several high-potential switching elements (111, 112, 113) connected to a high-potential line (Lh) and several low-potential switching elements (114, 115, 116) connected to a low-potential line (LI), which supplies electrical energy from a power supply to the motor (80); a first drive unit (51) that controls an operation of the high-potential switching elements (111, 112, 113); a first amplifier (61, 161) which is connected to the first drive unit (51), amplifies a voltage (Vb) from the power supply and outputs an amplified voltage (Vb_B1) to the first drive unit (51); a second drive unit (52) that controls an operation of the low-potential switching elements (114, 115, 116); a second amplifier (62, 162) which is connected to the second drive unit (52), amplifies the voltage (Vb) of the power supply and outputs another amplified voltage (Vb_B2) to the second drive unit (52), and a power supply voltage sensing unit (10) which senses the voltage (Vb) of the power supply, wherein: The second amplifier (62, 162) amplifies the voltage (Vb) of the power supply when the voltage (Vb) of the power supply is less than a power supply voltage threshold (Vb_th), The second amplifier (62, 162) does not amplify the power supply voltage (Vb) if the power supply voltage (Vb) is not less than the power supply voltage threshold (Vb_th), and the first amplifier (61, 161) always amplifies the voltage (Vb) of the power supply independently of the voltage (Vb) of the power supply.

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] The present application is based on the Japanese patent application JP 2017 - 029 883 A, filed on February 21, 2017, the disclosure of which is hereby incorporated by reference. [TECHNICAL FIELD]

[0002] The present disclosure relates to a control device and an electric power steering device that uses it. STATE OF THE ART

[0003] Traditionally, as described in JP 2013 - 163 515 A, an electric power steering device is known such that a so-called boost energy source (hereinafter referred to as the amplification energy source) is connected to a drive circuit. OVERVIEW OF THE INVENTION

[0004] In the configuration of the JP 2013-163515A, a booster power source is used to drive the switching element on the high-voltage side. The voltage from the power source is used to drive the switching element on the low-voltage side.

[0005] In recent years, a low-voltage drive has become necessary in electric power steering devices. With low-voltage control, in the configuration of the JP 2013-163 515 A, the voltage between the gate and source on the low-voltage side is not guaranteed, and the switching element is in a partially switched-on state. Consequently, the on-resistance (measured as a resistance value) increases rapidly when the switching element is fully switched on. As the on-resistance increases, so does the power loss. This can cause the temperature of the switching element to rise due to heat generation from the power loss, potentially leading to damage such as burnout.

[0006] Reference is also made to US 2011 / 0 115 289 A1, DE 10 2005 023 456 A1, EP 2 445 111 A2, DE 10 2014 113 105 A1 and JP 2006 - 333 561 A, which were identified as prior art.

[0007] One object of the present disclosure is to provide a control device and an electric power steering device with which a failure of a switching element is avoided even when the power supply voltage is reduced. This object is achieved by the features of the independent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing and further tasks, features and advantages of the present disclosure will become more apparent from the following detailed description in conjunction with the drawings.

[0009] They show: Fig. 1 a schematic structure diagram representing a steering system according to an exemplary embodiment; Fig. 2 a circuit diagram representing a motor control device according to an exemplary embodiment; Fig. 3 a block diagram showing a control unit of an engine control device according to an exemplary embodiment; Fig. 4 a circuit diagram to illustrate a first amplifier of the motor control device according to an exemplary embodiment; Fig. 5 a circuit diagram to illustrate a second amplifier of the motor control device according to an exemplary embodiment; Fig. 6 a flowchart to explain the processing operations of the engine control device according to an exemplary embodiment; Fig. 7 a circuit diagram to illustrate a first amplifier of the motor control device according to a further exemplary embodiment; and Fig. Figure 8 is a circuit diagram to explain a second amplifier of the motor control device according to a further exemplary embodiment. FORMS OF EXECUTION OF THE INVENTION

[0010] A control device according to one embodiment and an electric power steering device using this device are described below with reference to the drawings. In a multitude of embodiments, an substantially identical element is designated below with the same reference numeral to avoid duplication. When reference is made to the present embodiment, several embodiments may be included.

[0011] Here, an electric power steering device using a motor control device 1 as the control device of the present embodiment is described with reference to the drawings.

[0012] As in Fig. As shown in Figure 1, the electric power steering device 8 is used for a steering system 90.

[0013] The steering system 90 is mounted on a vehicle and includes a steering wheel 91, a steering shaft 92, a torque sensor 94, a pinion 96, a rack 97, wheels 98 and an electric power steering device 8.

[0014] The steering wheel 91 is a steering element and is connected to the steering shaft 92. The torque applied by a driver through the steering wheel 91 is defined as the steering torque.

[0015] A pinion 96 is provided at the tip of the steering shaft 92.

[0016] The torque sensor 94 can detect a steering torque. The detected steering torque is output to the control unit 30 of the motor control device 1.

[0017] The pinion 96 engages with the rack 97.

[0018] The rack 97 has a pair of wheels 98 which are connected to both ends of the rack 97 via a tie rod or the like.

[0019] The electric power steering device 8 includes a reduction gear 89, a motor 80 as a rotating electric machine, a rotation angle sensor 84 and the motor control device 1.

[0020] The electric power steering device 8 of the present embodiment is a so-called "column support device". Alternatively, the electric power steering device 8 can be a so-called "rack and pinion support device", which transmits the rotation of the motor 80 to the rack 97.

[0021] The reduction gear 89 reduces the rotation of the motor 80 and transmits it to the steering shaft 92.

[0022] A torque that assists the driver during the steering process of the steering wheel 91 is called a support torque.

[0023] Motor 80 outputs an auxiliary torque. Electrical energy is supplied to motor 80 by battery 5 as a "power supply," and motor 80 is driven. Motor 80 causes the reduction gear 89 to rotate in forward and reverse directions.

[0024] The rotary angle sensor 84, for example, is a rotary encoder and can detect the electrical angle θ of the motor 80. The detected electrical angle θ is output to the control unit 30.

[0025] The rotary angle sensor 84 can calculate the rotary angular velocity ω of the motor 80 based on the electrical angle θ. (Forms of execution)

[0026] As in Fig. As shown in Figure 2, motor 80 is a three-phase AC motor and a brushless motor.

[0027] The motor 80 has a winding set 81.

[0028] The winding set 81 comprises a U-phase coil 811, a V-phase coil 812, and a W-phase coil 813. One end of the coils 811, 812, and 813 is connected to the inverter 11, and the other end is connected to each other.

[0029] The motor control device 1 is connected to the battery 5 via the power supply connection 12 or the ignition connection 13.

[0030] The power supply connection 12 is connected to the high potential side of the battery 5.

[0031] The ignition terminal 13 is connected to the high potential side of the battery 5 via the ignition switch 14.

[0032] The motor control device 1 includes a power supply voltage sensing unit 10, an inverter 11, a motor current sensing unit 15, a substrate 17 and a heat sink 18.

[0033] Furthermore, the motor control device 1 includes a control unit 30, a first drive unit 51, a second drive unit 52, a first amplifier 61, a second amplifier 62, a gate voltage sensing unit 63, a first drive current sensing unit 64, a second drive current sensing unit 65 and an abnormality detection unit 66.

[0034] The power supply voltage detection unit 10 is connected to the battery 5 and can detect the power supply voltage Vb.

[0035] The power supply voltage detection unit 10 outputs the detected power supply voltage Vb to the first amplifier 61 and the second amplifier 62.

[0036] Inverter 11 is designed to correspond to winding set 81 and is a three-phase inverter.

[0037] The inverter 11 is connected to the PIG power supply line Lpig from the battery 5 via the power supply connection 12.

[0038] The inverter 11 has several high-potential switching elements 111 to 113 and several low-potential switching elements 114 to 116.

[0039] The high-potential switching elements 111 to 113 are connected to the high-potential line Lh.

[0040] The low-potential switching elements 114 to 116 are connected to the low-potential line LI.

[0041] Switching elements 111 to 116 are MOSFETs. Switching elements 111 to 116 can be IGBTs.

[0042] The connection point between the U-phase switching elements 111 and 114, which represent a pair, is connected to the first U-phase coil 811.

[0043] A connection point of the V-phase switching elements 112 and 115, which represent a pair, is connected to a first V-phase coil 812.

[0044] A connection point of the W-phase switching elements 113 and 116, which represent a pair, is connected to a first W-phase coil 813.

[0045] The motor current sensing unit 15 includes motor current sensing elements 151 to 153.

[0046] The motor current sensing elements 151 to 153 are, for example, shunt resistors or Hall elements.

[0047] The motor current sensing element 151 is arranged between the low potential switching element 114 and the ground line Lg1 and detects the U-phase current Iu flowing through the U-phase coil 811.

[0048] The motor current sensing element 152 is arranged between the low potential switching element 115 and the ground line Lg1 and detects a V-phase current Iv flowing through the V-phase coil 812.

[0049] The motor current sensing element 153 is arranged between the low potential switching element 116 and the ground line Lg1 and detects a W-phase current Iw flowing through the W-phase coil 813.

[0050] The substrate 17 carries each part of the motor control device 1.

[0051] The heat sink 18 has several ribs which are heat sink plates and can dissipate the heat from the switching elements 111 to 116 and 121 to 126.

[0052] The control unit 30 mainly comprises a microcomputer and the like. Any processing in the control unit 30 can be software processing in the CPU by executing a program pre-stored in a physical memory device such as ROM, or hardware processing performed by a dedicated electronic circuit.

[0053] The control unit 30 is connected to the ignition line Lig.

[0054] The control unit 30 controls the motor 80 by current feedback control based on the steering torque, the electrical angle θ and the phase currents Iu, Iv, Iw.

[0055] As in Fig. As shown in Figure 3, the control unit 30 includes a three-phase-to-two-phase converter 31, a temperature detector 37, a temperature estimation unit 38, a motor current limiting unit 39, subtractors 32 and 33, a controller 43, a two-phase-to-three-phase converter 35, and a PWM converter 36.

[0056] The three-phase-to-two-phase converter 31 performs a DC voltage conversion of the phase currents lu, Iv and Iw based on the electric angle θ.

[0057] Furthermore, the three-phase-to-two-phase converter 31 calculates the d-axis current detection value Id and the q-axis current detection value Iq.

[0058] The temperature detector 37, for example, is a thermistor, which is a ceramic semiconductor whose electrical resistance changes depending on the temperature. The temperature of the substrate 17 is defined as the substrate temperature Tb. The substrate temperature Tb also includes the atmospheric temperature around the substrate 17. The temperature of the heat sink 18 is defined as the heat sink temperature Th. The ambient temperature outside the motor control device 1 is defined as the outside air temperature Ta.

[0059] The temperature detector 37 can detect the substrate temperature Tb, the heat sink temperature Th, or the ambient air temperature Ta. The temperature detected by the temperature detector 35 is referred to as the detection temperature Td.

[0060] The temperature detector 37 outputs the detection temperature Td to the temperature estimation unit 38.

[0061] The temperature estimation unit 38 can estimate the element temperature Ts based on the dq-axis current sensing values ​​Id and Iq and the sensing temperature Td.

[0062] The temperature estimation unit 38 calculates the temperature change amount of the high-potential switching elements 111 to 113 and the low-potential switching elements 114 to 116 from the dq-axis current detection values ​​Id and Iq.

[0063] The temperature estimation unit 38 estimates the element temperature Ts by adding the detection temperature Td to the temperature change amount of the high potential switching elements 111-113 and the low potential switching elements 114-116.

[0064] The motor current limiting unit 39 limits the dq-axis current command values ​​Id* and Iq* based on the element temperature Ts. The limit of the d-axis current sensing value Id is set as the d-axis limit current Id_lim. The limit of the q-axis current sensing value Iq is set as the q-axis limit current Iq_lim. The d- and q-axis limit currents Id_lim and Iq_lim are set to decrease linearly as the element temperature Ts increases.

[0065] The current command values ​​before the limit are defined as pre-limit dq axis current command values ​​Id*_b and Iq*_b.

[0066] The motor current limiting unit 39 sets the d-axis current command value Id* as the d-axis limit current Id_lim if the pre-limit d-axis current command value Id*_b is greater than the d-axis limit current Id_lim.

[0067] If the pre-limit q-axis current command value Iq*_b is greater than the Q-axis limit current Iq_lim, the motor current limiting unit 39 sets the q-axis current command value Iq* as the Q-axis limit current Iq_lim.

[0068] The subtractor 32 calculates a deviation ΔId between the d-axis current command value Id* and the d-axis current acquisition value Id.

[0069] The subtractor 33 calculates a deviation ΔIq between the q-axis current command value Iq* and the q-axis current detection value Iq.

[0070] The controller 34 calculates the d-axis voltage command value Vd* and the q-axis voltage command value Vq* by PI calculation or the like, so that the deviations ΔId and ΔIq converge to zero.

[0071] The two-phase-to-three-phase converter 35 performs an inverse dq conversion of the DC voltage command value Vd* and the d-axis command value Vq* based on the electric angle θ.

[0072] Furthermore, the two-phase-to-three-phase converter calculates 35 voltage command values ​​Vu*, Vv* and Vw* in three phases.

[0073] The PWM converter 36 calculates the voltages to be applied to the high-potential switching elements 111 to 113 on the basis of the three-phase voltage command values ​​Vu*, Vv*, Vw* and generates the first drive signals UU, VU, WU.

[0074] The PWM converter 36 outputs the first drive signals UU, VU, WU to the first drive unit 51.

[0075] Furthermore, the PWM converter 36 calculates the voltages to be applied to the low-potential switching elements 114 to 116 on the basis of the three-phase voltage command values ​​Vu*, Vv* and Vw* and generates second drive signals UL, VL and WL.

[0076] The PWM converter 36 outputs the second drive signals UL, VL and WL to the second drive unit 52.

[0077] Inverter 11 is controlled to switch on and off based on the first drive signals UU, VU, WU and the second drive signals UL, VL, WL.

[0078] The first drive unit 51 can control the operation of the high-potential switching elements 111 to 113 based on the first drive signals UU, VU and WU.

[0079] The second drive unit 52 can control the operation of the low potential switching elements 114 to 116 based on the second drive signals UL, VL and WL.

[0080] The first amplifier 61 and the second amplifier 62 are integrally provided on the substrate 17. A microcomputer or the like can be mounted in the first amplifier 61 and the second amplifier 62.

[0081] The first amplifier 61 is connected to the battery 5 and the first drive unit 51 and amplifies the power supply voltage Vb. The voltage amplified by the first amplifier 61 is referred to as the first amplified voltage Vb_B1.

[0082] The first amplifier 61 outputs the first amplified voltage Vb_B1 to the first drive unit 51.

[0083] As in Fig. As shown in Figure 4, the first amplifier includes 61 diodes 611 and 612, capacitors 613 and 614 and switching elements 615 and 616.

[0084] Capacitor 614 is positioned closer to the output side than capacitor 613.

[0085] The voltage across capacitor 613 is defined as Vc. For example, when switching element 615 is switched off and switching element 616 is switched on, the voltage Vc is applied to capacitor 613 by the supply voltage Vb. The voltage Vc is expressed by the following equation (1). Here, voltage Vf is a voltage that relates to a forward direction of each of diodes 611 and 612. Vc=Vb−Vf

[0086] After the capacitor 613 is charged, when the switching element 615 switches on and the switching element 616 switches off, the first amplified voltage Vb_B1 is expressed by the following equation (2). Vb−B1=Vb+Vc−Vf=2Vb−2VF

[0087] The first amplified voltage Vb_B1 is used to charge the gates of the high-potential switching elements 111 to 113. The amount of gate charge required to switch on the high-potential switching elements 111 to 113 is defined as Qg1. The charge of capacitor 414 is defined as Q1.

[0088] The values ​​Qg1 and Q1 are set such that they satisfy the following equation (3). Here, n is the number of high-potential switching elements 111 to 113. In the present embodiment, n = 3. Capacitor 613 is set such that it charges capacitor 614. Qg1×n <Q1

[0089] The second amplifier 62 is connected to the battery 5 and the second drive unit 52 and amplifies the power supply voltage Vb. The second amplifier 62 is configured to amplify the power supply voltage Vb when the power supply voltage Vb is less than the power supply voltage threshold Vb_th. The power supply voltage threshold Vb_th is predetermined and determined through experimentation, simulation, or similar methods. The voltage amplified by the second amplifier 62 is referred to as the second amplified voltage Vb_B2.

[0090] Furthermore, the first amplified voltage Vb_B1 is set such that it is greater than the second amplified voltage Vb_B2, that is, that it has a relationship of equation (4). Vb_B1>Vb_B2

[0091] The second amplifier 62 outputs the second amplified voltage Vb_B2 to the second drive unit 52.

[0092] As in Fig. As shown in Figure 5, the second amplifier includes 62 diodes 621 and 622, capacitors 623 and 624 and switching elements 625 and 626.

[0093] Similar to the first amplifier 61, the second amplifier 62 amplifies the power supply voltage Vb.

[0094] The second amplified voltage, Vb_B2, is used to charge the gates of the low-potential switching elements 114 to 116. The amount of gate charge required to switch on the low-potential switching elements 114 to 116 is defined as Qg2. The charge of capacitor 624 is defined as Q2.

[0095] The values ​​Qg2 and Q2 are set such that they satisfy the following equation (5). Here, m is the number of low-potential switching elements 114 to 116. In the present embodiment, m = 3. Capacitor 623 is set to charge capacitor 624. Qg2×m <Q2

[0096] A voltage applied between the second drive unit 52 and the low-potential switching elements 114 to 116 is defined as a gate voltage Vg.

[0097] The gate voltage detection unit 63 can detect the gate voltage Vg.

[0098] The gate voltage detection unit 63 also outputs the detected gate voltage Vg to the second drive unit 52.

[0099] The second drive unit 52 performs feedback control based on the gate voltage Vg, so that the gate voltage Vg assumes a predetermined value.

[0100] The gate voltage minimum (Vg_min) and maximum (Vg_max) are defined in terms of the gate voltage (Vg). These minimum and maximum values ​​are predetermined and determined through experimentation, simulation, or similar methods.

[0101] The second drive unit 52 increases the gate voltage Vg when the gate voltage Vg is less than the lower limit of the gate voltage lower limit Vg_min.

[0102] Furthermore, if the gate voltage Vg is greater than the gate voltage limit Vg_max, the second drive unit 52 reduces the gate voltage Vg.

[0103] The current flowing through the first drive unit 51 is referred to as the current Is1 of the first drive unit.

[0104] The first drive current detection unit 64 is provided in the first drive unit 51 and can detect the current Is1 of the first drive unit.

[0105] The first drive current detection unit 64 is, for example, a shunt resistor or a Hall element.

[0106] The first drive current detection unit 64 outputs the detected current Is1 of the first drive unit to the abnormality determination unit 66.

[0107] The current flowing through the second drive unit 52 is referred to as the current Is2 of the second drive unit.

[0108] The second drive current detection unit 65 is provided in the second drive unit 52 and can detect the current Is2 of the second drive unit.

[0109] The second drive current detection unit 65 is, for example, a shunt resistor or a Hall element.

[0110] The second drive current detection unit 65 outputs the detected current Is2 of the second drive unit to the abnormality determination unit 66.

[0111] The abnormality detection unit 66 determines that the first drive unit 51 is abnormal if the current Is1 of the first drive unit is equal to or greater than a predetermined threshold Is1_th.

[0112] If the abnormality detection unit 66 determines that the first drive unit 51 is abnormal, the first drive unit 51 stops controlling the high-potential switching elements 111 to 113.

[0113] Furthermore, the abnormality detection unit 66 determines that the second drive unit 52 is abnormal if the current Is2 of the second drive unit is equal to or greater than a predetermined threshold Is2_th.

[0114] If the abnormality detection unit 66 determines that the second drive unit 52 is abnormal, the second drive unit 52 stops controlling the low-potential switching elements 114 to 116. The predetermined threshold values ​​Is1_th and Is2_th are set in advance and are determined through experiments, simulations, and the like.

[0115] The processing of the motor control device 1 is carried out with reference to the flowchart of Fig. 6 described. In the flowchart of the drawing, the symbol "S" represents a step.

[0116] In step S101, the second amplifier 62 determines whether the power supply voltage Vb is less than the power supply voltage threshold Vb_th.

[0117] If the power supply voltage Vb is less than the power supply voltage threshold Vb_th, processing continues with step S102.

[0118] If the power supply voltage Vb is equal to or greater than the power supply voltage threshold Vb_th, the processing ends.

[0119] In step S102, the second amplifier 62 amplifies the power supply voltage Vb.

[0120] In step S103, the second drive unit 52 determines whether the gate voltage Vg is less than the gate voltage lower limit Vg_min.

[0121] If the gate voltage Vg is less than the x gate voltage lower limit Vg_min, processing continues with step S104.

[0122] If the gate voltage Vg is equal to or greater than the gate voltage lower limit Vg_min, processing continues with step S105.

[0123] In step S104, the second drive unit 52 increases the gate voltage Vg and the processing ends.

[0124] In step S105, the second drive unit 52 determines whether the gate voltage Vg is greater than the upper gate voltage limit Vg_max.

[0125] If the gate voltage Vg is greater than the upper limit of the gate voltage Vg_max, processing continues with step S106.

[0126] If the gate voltage Vg is equal to or less than the upper limit of the gate voltage Vg_max, processing continues with step S107.

[0127] In step S106, the second drive unit 52 reduces the gate voltage Vg and the processing ends.

[0128] In step S107, the abnormality detection unit 66 determines whether the first drive unit 51 or the second drive unit 52 is abnormal.

[0129] If the abnormality detection unit 66 determines that the first drive unit 51 or the second drive unit 52 is abnormal, processing continues with step S108.

[0130] When the abnormality detection unit 66 determines that the first drive unit 51 and the second drive unit 52 are normal, the processing ends.

[0131] If in step S108 the abnormality detection unit 66 determines that the first drive unit 51 is abnormal, the first drive unit 51 stops controlling the high-potential switching elements 111 to 113 and the processing ends.

[0132] If the abnormality detection unit 66 determines in step S108 that the second drive unit 52 is abnormal, the second drive unit 52 stops controlling the low-potential switching elements 114 to 116 and processing ends.

[0133] Traditionally, as described in Patent Document 1, an electric power steering device is known such that an amplifying energy source is connected to a drive circuit. In recent years, a low-voltage drive has been required in an electric power steering device. With low-voltage drives, the voltage between the gate and source on the low-voltage side is not guaranteed, and the switching element is in a partially switched-on state. For this reason, the on-resistance, measured as a resistance value, increases rapidly when the switching element is in the fully switched-on state. As the on-resistance increases, the power loss also increases. Consequently, the temperature of the switching element can rise due to heat generation from the power loss, and the switching element can be damaged, for example, by burning out.

[0134] Therefore, the motor control device of the present embodiment can prevent the failure of the switching element even when the power supply voltage is reduced.

[0135] [1] Since the second amplifier 62 is connected to the second drive unit 52 and the second amplified voltage Vb_B2 is supplied to the second drive unit 52, the switching elements 114 to 116 are not in a half-on state. As a result, the on-resistance is prevented from rising rapidly, and the power loss is reduced. Consequently, it is possible to avoid a fault such as a burning out of the switching element.

[0136] [2] The second amplifier 62 amplifies the power supply voltage Vb when the power supply voltage Vb is less than the power supply voltage threshold Vb_th. This allows the second amplifier 62 to be sized according to the required voltage. The size of the second amplifier 62 can be minimized compared to the case where the amplifier is designed to function like an inverter, simply to prevent a drop in the input voltage to the control device.

[0137] [3] The second drive unit 52 performs feedback control based on the gate voltage Vg. This improves the controllability of the low-potential switching elements 114 to 116 by the second drive unit 52.

[0138] [4] The abnormality detection unit 66 determines that the second drive unit 52 is abnormal if the current Is2 of the second drive unit is equal to or greater than the predetermined threshold Is2_th, and the unit 52 stops controlling the low-potential switching elements 114-116. This prevents overcurrent to the low-potential switching elements 114-116 and damage to the low-potential switching elements 114-116. (Other embodiments)

[0139] (i) The motor is not limited to a three-phase AC motor, but may be a four-phase or an AC motor with even more phases. Three or more sets of motors may also be provided. The number of sets may be three or more. Furthermore, the motor may be a generator or a motor-generator, which has the functions of both a motor and a generator.

[0140] (ii) In the present embodiment, the motor and the motor control device are integrally provided. Alternatively, the motor and the motor control device can be provided separately.

[0141] (iii) The amplifier is not limited to the switching converter system and can perform amplification through another system such as a linear system.

[0142] (iv) A capacitor, a power supply relay, a reverse polarity protection relay or a choke coil may be provided between the battery and the inverter.

[0143] The capacitor is connected in parallel to the battery and has the function of suppressing normal mode noise from the battery and smoothing voltage fluctuations from the battery.

[0144] The power supply relay is designed according to the winding set, which is located between the battery and the inverter and connected to the high-potential line. The power supply relay is a MOSFET. The power supply relay can be an IGBT or a mechanical relay.

[0145] The power supply relay directs or interrupts the current from the battery to the inverter.

[0146] The reverse polarity protection relay is located between the inverter and the power supply relay.

[0147] The reverse polarity protection relay, like the power supply relay, is a MOSFET. Furthermore, the reverse polarity protection relay is connected so that the direction of the parasitic diode is opposite to that of the power supply relay.

[0148] The reverse polarity protection relay interrupts the reverse polarity current from the inverter to the power supply relay if the battery is connected in the wrong direction. Thus, the reverse polarity protection relay protects the engine control unit.

[0149] The choke coil has a structure in which a conductor is wound around a core and is installed between the battery and the power supply relay. The choke coil generates a magnetic flux when current flows. Due to the generated magnetic flux, the choke coil acts as an inductor and suppresses noise.

[0150] (v) The first amplifier 61 and the second amplifier 62 can be configured such that the first amplified voltage Vb_B1 and the second amplified voltage Vb_B2 are three times or more than the power supply voltage Vb. In this case, the number of diodes, the number of capacitors, and the number of switching elements in the first amplifier and the second amplifier are increased according to the multiple of the power supply voltage Vb.

[0151] As in Fig. As shown in Figure 7, the first amplifier 161 further includes a diode 617, a capacitor 618 and switching elements 619 and 620, which are arranged between the capacitor 613 and the capacitor 614, so that the first amplified voltage Vb_B1 is three times greater than the power supply voltage Vb.

[0152] As in the embodiment, the voltage across capacitor 613 is defined as Vc. Similar to an embodiment, Vc is expressed as in equation (1). The voltage Vc is applied to capacitor 613.

[0153] The voltage assigned to capacitor 618 is defined as Vc_ad.

[0154] After capacitor 613 is charged, when switching element 615 turns on, switching element 616 turns off, switching element 619 turns off, and switching element 620 turns on, the voltage Vc_ad is expressed by the following equation (6). The voltage Vc_ad changes in capacitor 618. Vc_ad=Vb+Vc−Vf=2Vb−2Vf

[0155] After capacitor 618 is charged, when switching element 619 turns on and switching element 620 turns off, the first amplified voltage Vb_B1 is expressed by the following equation (7). This drives switching elements 615, 616, 619, and 620 to amplify the voltage. For example, by synchronously driving switching elements 615 and 620 and synchronously driving switching elements 616 and 619, the amplification can be carried out in a short time. The charges of capacitor 614 and capacitor 624 are set according to multiples of the power supply voltage Vb. Vb_B1=Vb+Vc_ad−Vf=3Vb−3VF

[0156] As in Fig.As shown in Figure 8, the second amplifier 162 further includes a diode 627, a capacitor 628 and switching elements 629 and 630, which are arranged between the capacitor 623 and the capacitor 624, so that the second amplified voltage Vb_B2 is three times greater than the power supply voltage Vb.

[0157] The second amplifier 162 is driven in the same way as the first amplifier 161 described above. The second amplified voltage Vb_B2 triples the power supply voltage Vb.

[0158] (Vi) A voltage converter may be provided between the battery and the control unit.

[0159] The present disclosure is not limited to the embodiments described above, but various modifications may be made within the scope of the present disclosure without deviating from the spirit of the disclosure.

[0160] The present disclosure was made according to the embodiments shown. However, the present disclosure is not limited to such embodiments and configurations. The present disclosure also includes various modifications and variations within the scope of equivalents. Furthermore, various combinations and formations, as well as other combinations and formations including one, more than one, or fewer than one element, may be made in the present disclosure.

Claims

[1] A control device for controlling a motor (80) rotated by electrical energy, the control device comprising: an inverter (11) having a plurality of high-potential switching elements (111, 112, 113) connected to a high-potential line (Lh) and a plurality of low-potential switching elements (114, 115, 116) connected to a low-potential line (LI), which supplies electrical energy from a power supply to the motor (80); a first drive unit (51) that controls an operation of the high-potential switching elements (111, 112, 113); a first amplifier (61, 161) connected to the first drive unit (51), amplifying a voltage (Vb) of the power supply and outputting an amplified voltage (Vb_B1) to the first drive unit (51); a second drive unit (52) that controls an operation of the low-potential switching elements (114, 115, 116); a second amplifier (62, 162) connected to the second drive unit (52), amplifying the voltage (Vb) of the power supply and outputting another amplified voltage (Vb_B2) to the second drive unit (52), and a power supply voltage detection unit (10) which detects the voltage (Vb) of the power supply, wherein: the second amplifier (62, 162) amplifies the voltage (Vb) of the power supply when the voltage (Vb) of the power supply is less than a power supply voltage threshold value (Vb_th), the second amplifier (62, 162) does not amplify the voltage (Vb) of the power supply if the voltage (Vb) of the power supply is not less than the power supply voltage threshold value (Vb_th), and the first amplifier (61, 161) always amplifies the voltage (Vb) of the power supply independently of the voltage (Vb) of the power supply. [2] Control device according to claim 1, wherein: the amplified voltage (Vb_B1) of the first amplifier (61, 161) is greater than the other amplified voltage (Vb_B2) of the second amplifier (62, 162). [3] Control device according to one of claims 1 to 2, further comprising: a gate voltage detection unit (63) that detects a gate voltage (Vg) applied between the second drive unit (52) and the low-potential switching elements (114, 115, 116), wherein: the second drive unit (52) performs feedback control based on the gate voltage (Vg). [4] Control device according to claim 3, wherein: the second drive unit (52) increases the gate voltage (Vg) when the gate voltage (Vg) is less than a lower limit value (Vg_min); and the second drive unit (52) reduces the gate voltage (Vg) when the gate voltage (Vg) is greater than an upper limit value (Vg_max). [5] Control device according to one of claims 1 to 4, further comprising: an abnormality determination unit (66) that determines an abnormality of the first drive unit (51) or the second drive unit (52), wherein: when the abnormality determination unit (66) determines that the first drive unit (51) is abnormal, the first drive unit (51) stops controlling the high-potential switching elements (111, 112, 113); and when the abnormality determination unit (66) determines that the second drive unit (52) is abnormal, the second drive unit (52) stops controlling the low-potential switching elements (114, 115, 116). [6] Control device according to one of claims 1 to 5, wherein: the first amplifier (61, 161) and the second amplifier (62, 162) are arranged integrally on a substrate (17). [7] Control device according to one of claims 1 to 6, wherein: the temperature of the high-potential switching elements (111, 112, 113) or the low-potential switching elements (114, 115, 116) is defined as an element temperature (Ts), the control device further comprises: a temperature estimation unit (38) that estimates the element temperature (Ts); and a motor current limiting unit (39) that limits the current flowing in the motor (80) based on the element temperature (Ts). [8] Electric power steering device, comprising: a motor (80) that outputs an assist torque for assisting a driver's steering operation; and the control device (1) according to one of claims 1 to 7.

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