JP2009089531A - Motor temperature estimation unit and electric power steering device mounting it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor temperature estimation device which can estimate the temperature of a polyphase motor correctly in principle while taking account of the temperature difference of each phase coil of the polyphase motor and the rotational speed of the motor. <P>SOLUTION: A temperature sensor for detecting the temperature of a control board for controlling a polyphase motor inputs a detection temperature, a temperature estimation model of each phase is constituted based on heat conduction phenomenon between arbitrary phases caused by temperature difference of each phase coil of the polyphase motor and heat conduction phenomenon of the control board, and the resistance and inductance of a temperature estimation model of each phase are corrected by each temperature estimation value thereof thus estimating the coil temperature of each phase of the polyphase motor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor temperature estimation device for estimating the temperature of a multiphase motor and an electric power steering device equipped with the motor temperature estimation device, and in particular, considering a heat conduction phenomenon between phases caused by a temperature difference of each phase of the motor, more accurately the motor. The present invention relates to a temperature estimation device capable of estimating temperature and an electric power steering device equipped with the temperature estimation device.

  An electric power steering device for energizing a vehicle steering device with an auxiliary load by the rotational force of a motor energizes an auxiliary load to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a reduction gear. It is supposed to be. Such a conventional electric power steering apparatus performs feedback control of motor current in order to accurately generate assist torque (steering assist force). In the feedback control, the motor applied voltage is adjusted so that the difference between the current command value and the motor current detection value becomes small. Generally, the adjustment of the motor applied voltage is a duty of PWM (pulse width modulation) control. This is done by adjusting the tee ratio.

  Here, the general configuration of the electric power steering apparatus will be described with reference to FIG. 6. The column shaft 2 of the handle 1 is connected to a tie rod 6 of a steered wheel via a reduction gear 3, universal joints 4 A and 4 B and a pinion rack mechanism 5. It is connected to. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the handle 1, and a motor 20 that assists the steering force of the handle 1 is connected to the column shaft 2 via the reduction gear 3. A power is supplied from the battery 13 to the control unit 30 that controls the power steering device, and an ignition signal is input through the ignition key 11. The control unit (ECU) 30 detects the steering torque detected by the torque sensor 10. A steering assist command value I of the assist command is calculated based on Th and the vehicle speed V detected by the vehicle speed sensor 12, and a current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

  The control unit 30 is mainly composed of a CPU (including MPU and MCU). FIG. 7 shows general functions executed by a program inside the CPU.

The function and operation of the control unit 30 will be described with reference to FIG. 7. The steering torque Th detected and input by the torque sensor 10 and the vehicle speed V from the vehicle speed sensor 12 are input to the steering assist command value calculation unit 31. Thus, the steering assist command value Iref1 is calculated. The calculated steering assist command value Iref1 is phase compensated by the phase compensator 32 for enhancing the stability of the steering system, and the phase compensated steering assist command value Iref2 is input to the adder 33. Further, the steering torque Th is input to the feedforward differential compensation unit 35 for increasing the response speed, and the differentially compensated steering torque TAh is input to the addition unit 33, which adds the steering assist command value Iref2 and the steering. The torque TAh is added, and the current command value Iref3 as the addition result is input to the subtracting unit 34.
When the motor 20 is a three-phase motor, the subtracting unit 34 obtains a deviation Iref4 (= Iref3-i) between the current command value Iref3 (three-phase) and the fed-back motor current i (three-phase). The deviation Iref4 is PI-controlled by the PI control unit 36, and further input to the PWM control unit 37 to calculate the duty, and the motor 20 is PWM-driven via the inverter 38. The motor current value i of the motor 20 is detected by a motor current detecting means (not shown), and is input to the subtracting unit 34 and fed back.

  Since the motor 20 is a three-phase motor, the details of the PWM control unit 37 and the inverter 38 are configured as shown in FIG. 8, for example. The PWM control unit 37 receives the voltage command value E from the PI control unit 36. A duty calculation unit 371 that calculates PWM duty values D1 to D6 for three phases according to a predetermined formula, and drives each gate of FET1 to FET6 as drive elements with PWM duty values D1 to D6 and compensates for dead time. The inverter 38 is composed of a three-phase bridge of FET1 to FET6 to which the battery voltage VR is supplied, and is turned on / off with PWM duty values D1 to D6. To drive the motor 20.

  In such an electric power steering device, since a large current (usually 30A to 60A, and in some cases 100A) flows through the motor, it is necessary to take protective measures against overheating of the motor and the like from the viewpoint of vehicle safety, and the motor temperature is estimated. Alternatively, overheat protection means for detecting and overheating is provided in the ECU.

  Conventionally, as shown in Japanese Patent Publication No. 6-51474 and Japanese Patent No. 2528119, based on the motor current detection value, an average value in a predetermined time is obtained from the current value, and current limitation is performed. The motor is protected from overheating by a measure that limits the current every predetermined time when the average current is a predetermined value or more.

  The conventional method limits the motor current by estimating the calorific value from the motor current, but since the absolute temperature is not taken into account, the estimated temperature depends on the outside temperature where the vehicle is placed. In some cases, the motor and the motor drive circuit of the ECU cannot be sufficiently protected. In addition, if the temperature (threshold) for overheating protection is set assuming a high temperature, the protection function is activated quickly at room temperature or low temperature, and the time during which a large current can be output during stationary operation is reduced.

  Further, in the conventional method, the motor current is limited by measuring only the temperature of the radiator of the control unit (ECU), or the motor current is limited by estimating the motor temperature. However, since the thermal time constant of the ECU radiator is different from the thermal time constant of the motor, for example, if only the radiator of the ECU is measured and the motor current is limited to perform overheat protection, the motor temperature will not decrease before the motor temperature decreases. There is a possibility that the current limitation is canceled and the motor is damaged.

  In order to solve such various problems, for example, Japanese Patent No. 3601967 (Patent Document 1) proposes an electric power steering apparatus provided with an overheat protection means. The overheat protection means disclosed in Patent Document 1 includes overheat protection by a temperature sensor in the ECU, estimates the temperatures of the motor brush and the magnetic body (magnet) based on the ECU temperature, It is carried out. Moreover, in the motor temperature estimation apparatus shown by Unexamined-Japanese-Patent No. 2006-115553 (patent document 2), motor temperature is estimated from the board | substrate temperature and electric current which were obtained from the temperature sensor on a circuit board. That is, the offset temperature is obtained from the difference between the circuit board temperature and the motor ambient temperature, and the motor temperature is estimated by adding the motor heat generation amount and the natural heat dissipation amount to the offset value.

Furthermore, in Japanese Patent Laid-Open No. 2006-42466 (Patent Document 3), in a three-phase motor, for example, the amount of heat generated in the U phase is obtained from the current in the U phase, and between the windings based on the temperature difference of each winding (coil). The amount of heat transferred is obtained, the amount of heat given to the motor is obtained from the outside air temperature, and the U-phase winding temperature is obtained from the total amount. The same processing is performed for the VW phase of the other phase. Moreover, in the motor temperature estimation apparatus shown by Unexamined-Japanese-Patent No. 2003-284375 (patent document 4), the square of a motor electric current carries out a low-pass filter process, Based on this result, a mass part (housing or stator), a coil part The temperature increase is calculated, and the processing of the low-pass filter is made different depending on the stop state and the rotation state based on the rotation speed of the motor.
Japanese Patent No. 3601967 JP 2006-115553 A JP 2006-42466 A JP 2003-284375 A

  However, the apparatuses disclosed in Patent Documents 1 and 2 have no problem in terms of accuracy of temperature estimation because none of the effects of the temperature difference of each phase coil of the multiphase motor and the motor rotation speed are taken into consideration. Further, in the device of Patent Document 3, since the environmental temperature of the multiphase motor is detected by an external temperature sensor, there is a problem such as disconnection, and the motor rotation speed is considered in the heat dissipation coefficient of each phase coil of the motor. Not done. Although the heat conduction state when the motor rotates changes, the temperature is estimated using a temperature estimation model with a constant heat radiation coefficient, which causes an error in temperature estimation.

  Furthermore, in the apparatus described in Patent Document 4, although the motor rotation speed is taken into consideration, the temperature difference between the phases of each phase coil of the multiphase motor is not taken into consideration, and only two states of stop and rotation are separated. Therefore, there is a problem that the motor rotation speed cannot display the analog influence on the heat transfer coefficient in the temperature estimation model. Further, since the temperature estimation model is always constant and the correction of the temperature estimation model is not considered even if the motor temperature changes, there is a problem that the temperature cannot always be estimated with high accuracy.

  More accurate estimation of motor coil temperature or motor magnet temperature for modification of multi-phase motor parameters (resistance, inductance, etc.), motor overheat protection, or for efficient and reliable overheat protection of electric power steering system There is a need to. Since the motor used in the electric power steering apparatus affects the safety and steering feeling of the driver and the like, the overheat protection is extremely important.

  The present invention has been made under the circumstances as described above, and the object of the present invention is to accurately determine the temperature of the multiphase motor in principle, taking into account the temperature difference of each phase coil of the multiphase motor and the motor rotation speed. An object of the present invention is to provide a motor temperature estimation device capable of estimation. It is also an object of the present invention to provide a highly reliable electric power steering device that is equipped with the motor temperature estimation device and efficiently performs overheat protection.

  The present invention relates to a motor temperature estimation device, and the object of the present invention is to input a detection temperature from a temperature sensor that detects the temperature of a control board that controls the multiphase motor, and to detect the temperature difference between the phase coils of the multiphase motor. Each phase temperature estimation model is configured based on the generated heat conduction phenomenon between arbitrary phases and the heat conduction phenomenon of the control board, and the resistance and inductance of each phase temperature estimation model according to each temperature estimation value of each phase temperature estimation model And detecting a temperature from a temperature sensor that detects the temperature of a control board that controls the multiphase motor, by estimating the temperature of each phase coil of the multiphase motor, and the magnet of the multiphase motor and the A temperature estimation model is configured based on the heat conduction phenomenon of the control board, and the resistance and inductance of the temperature estimation model are determined by the temperature estimation value of the temperature estimation model. Chest, wherein correcting the torque constant and the back electromotive force constant of the polyphase motor is accomplished by estimating the magnet temperature of the polyphase motor.

  The present invention also relates to a motor temperature estimation device, and the object of the present invention is to detect a temperature of a control board that controls the multiphase motor, a detected temperature from the temperature sensor, and each phase of the multiphase motor. The motor current value or the current command value is input, and each phase coil temperature is estimated based on the heat conduction phenomenon between arbitrary phases caused by the temperature difference of each phase coil of the multiphase motor and the heat conduction phenomenon of the control board. A phase temperature estimation model, and correcting the resistance and inductance of each phase temperature estimation model according to each phase coil temperature, and correcting the coefficient of each phase temperature estimation model based on the rotational speed of the multiphase motor. Output a temperature of each phase coil, or a temperature sensor for detecting the temperature of a control board for controlling a multi-phase motor, a detected temperature from the temperature sensor and a previous temperature Provided is a temperature estimation model for inputting each phase motor current value or current command value of the multiphase motor and estimating the magnet temperature of the multiphase motor based on the heat conduction phenomenon of the magnet of the multiphase motor and the control board. Correcting the resistance and inductance of the temperature estimation model, the torque constant and back electromotive force constant of the multiphase motor according to the magnet temperature, and correcting the coefficient of the temperature estimation model based on the rotational speed of the multiphase motor. This is achieved by outputting the magnet temperature.

  Furthermore, the present invention relates to an electric power steering apparatus, and the object of the present invention is to input a detected temperature from a temperature sensor that detects the temperature of a control board that controls the multiphase motor, and to detect the temperature of each phase coil of the multiphase motor. Each phase temperature estimation model is configured based on the heat conduction phenomenon between the arbitrary phases caused by the difference and the heat conduction phenomenon of the control board, and the resistance of each phase temperature estimation model is determined by each temperature estimation value of each phase temperature estimation model. And a motor temperature estimation device that corrects the inductance and estimates each phase coil temperature of the multiphase motor, or inputs a detected temperature from a temperature sensor that detects the temperature of a control board that controls the multiphase motor, The temperature estimation model is configured based on the heat conduction phenomenon of the magnet of the multiphase motor and the control board, and the temperature estimation value of the temperature estimation model A motor temperature estimation device for correcting the resistance and inductance of the degree estimation model, the torque constant and the back electromotive force constant of the multiphase motor, and estimating the magnet temperature of the multiphase motor is mounted, and the temperature estimation of the motor temperature estimation device This is achieved by performing an overheat protection function and an output limiting function by value.

  According to the motor temperature estimation apparatus of the present invention, a temperature estimation model is constructed in consideration of the relationship between the heat transfer phenomenon and the motor rotation speed between each phase coil of the multiphase motor and the relationship between the heat dissipation coefficient and the motor rotation speed. Therefore, the motor temperature (coil, magnet) can be estimated with higher accuracy.

  In addition, by mounting a highly accurate temperature estimation device on the electric power steering device, more efficient and reliable overheat protection and output limitation can be performed.

  In a multiphase motor, when the energization current of each phase coil is not the same, the heat generation power (FET, shunt resistance, harness, etc.) is also not the same, so a temperature difference occurs between the phases, and this temperature difference causes any two phases Heat transfer phenomena such as heat conduction, heat radiation, and heat convection occur between the arbitrary phase coil and the outside air environment or magnet. Since various heat transfer methods of the multiphase motor are affected by the motor rotation speed, accurate temperature estimation cannot be performed unless the motor rotation speed is taken into account.

  For this reason, the motor temperature estimation device according to the present invention identifies a heat transfer coefficient between an arbitrary phase coil and an outside environment of a multiphase motor and an arbitrary phase and another phase based on a change in motor rotation speed, and a motor control unit (ECU ) To detect the substrate temperature with the temperature sensor mounted on the substrate, the sum of the square value of each phase current (or current command value) and the square value of each phase current (or current command value), the ECU substrate temperature rise value, The estimated temperature of each phase is input to a temperature estimation device that modifies parameters (resistance, inductance, etc.) according to the motor rotation speed and estimated temperature, and the temperature of each phase coil or magnet of the motor is accurately estimated.

  As described above, in the present invention, the temperature estimation model is constructed in consideration of the relationship between the heat transfer phenomenon between the multiphase coils and the motor rotation speed, and the relationship between the heat dissipation coefficient and the motor rotation speed. The motor temperature (coil, magnet) can be estimated well.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration example in which the temperature estimation device 100 of the present invention is mounted on an electric power steering device, corresponding to FIG. In this example, a three-phase (A, B, C phase) AC motor 20 will be described as an example. A temperature sensor 201 for detecting a control unit (ECU) board temperature is mounted on the control board of the ECU, and the board temperature detected by the temperature sensor 201 is input to the temperature estimation apparatus 100 by predetermined sampling. Further, the motor current values i _A , i _B , i _{C of} the motor 20 are also detected by a current detection means (not shown) and input to the temperature estimation device 100. Further, the separately calculated or detected motor rotation speed ω is also input to the temperature estimation device 100. Instead of the motor current values i _A , i _B , and i _C for each phase, a current command value (three phases) Iref 3 may be input to the temperature estimation device 100.

The motor coil temperature T _N (N = A, B, C) or the motor magnet temperature T _M estimated by the temperature estimation device 100 is input to the overheat protection means 200 and the output limiting means 202, and the motor coil temperature T _N or the motor magnet. when the temperature T _M has exceeded the threshold, the overheat protecting means 200 performs the limitation of the current command value (the steering assist command value) and the maximum current value and the like in a known manner, overheat protection of the motor 20 or the electric power steering device And output restriction. For example, when the temperature is low, the motor torque increases and may damage the mechanism, so the motor output is limited.

  Initially, the example (1st Embodiment) which estimates each phase coil temperature of the three-phase motor 20 is demonstrated. However, as a premise of estimation, it is assumed that the initial temperatures of the ECU, the coil, and the magnet are the same, and the final temperatures of the ECU, the coil, and the magnet are also the same for the estimation end condition.

  First, the temperature of the control board of the ECU is expressed by the following formula 1.

ただし、ΔＴ_ＥはＥＣＵの温度上昇値、Ｔ_ＥＯはＥＣＵの初期温度、Ｃ_ＥはＥＣＵの 熱容量、Ｒ_ＥはＥＣＵ発熱等価抵抗、ｉ_Ａ，ｉ_Ｂ，ｉ_Ｃは３相のモータ電流値、Ｋ_Ｅ は放熱係数、Ｔ_ＣはＥＣＵとモータの環境温度である。また、Ｑ_ＥはＥＣＵ部分の発 熱パワー（ＦＥＴ、ダイオード、シャント抵抗、リレー、ハーネス等）に相当してお り、

と表示され、簡易的には

と表示される。

Where ΔT _E is the ECU temperature rise value, T _EO is the initial temperature of the ECU, C _E is the heat capacity of the ECU, R _E is the ECU heat generation equivalent resistance, i _A , i _B and i _C are the three-phase motor current values, K _E is the radiation coefficient, _{T C} is the ambient temperature of the ECU and the motor. Also, _{Q E} is Ri Contact correspond to heat generation power of the ECU part (FET, diode, a shunt resistor, a relay, a harness and the like),

Is displayed.

Is displayed.

The ECU's heat capacity C _E , ECU heat generation equivalent resistance R _E , and heat dissipation coefficient _KE are known, the ECU temperature rise value ΔT _E , and the ECU initial temperature T _EO can be obtained from the temperature detected by the temperature sensor 201. The heat generation power Q _{E of the} portion can also be obtained from the motor current values i _A , i _B , i _C and the heat generation equivalent resistance R _E. Therefore, from Equation 1, it is possible to determine the environmental temperature _{T C} of the ECU and the motor.

  Further, the thermal equations of the three-phase coils A, B, and C are expressed by the following formula 2, respectively.

ただし、ΔＴ_Ａ，ΔＴ_Ｂ，ΔＴ_Ｃはそれぞれ３相コイルＡ，Ｂ，Ｃの温度上昇値、Ｔ _ＡＯ，Ｔ_ＢＯ，Ｔ_ＣＯはそれぞれ３相コイルＡ，Ｂ，Ｃの初期温度、Ｃ_Ｌはコイルの 熱容量、Ｋ_Ｌはモータの回転速度ωの関数とする外気温度への伝熱係数、Ｋ_Ｘはモー タの回転速度ωの関数とする各相の伝熱係数である。また、Ｑ_Ａ，Ｑ_Ｂ，Ｑ_Ｃはそれ ぞれ各相の発熱パワーを示しており、Ａ相抵抗をＲ_Ａ、Ｂ相抵抗をＲ_Ｂ、Ｃ相抵抗を Ｒ_Ｃとして、それぞれ

と表示される。

_{However, ΔT A, ΔT B, ΔT} C each 3-phase coils A, B, the temperature rise value of _{C, T AO, T BO,} T CO is 3-phase coils A, respectively, B, C initial temperature of, _{C L} is The heat capacity of the coil, K _L is the heat transfer coefficient to the outside air temperature as a function of the motor rotation speed ω, and K _X is the heat transfer coefficient of each phase as a function of the motor rotation speed ω. _Also, Q _A, Q B, _{Q C} is, the heating power of, respectively it phases, phase A resistor _R A, a B-phase resistance _R B, and C phase resistance as R _C, respectively

Is displayed.

Seeking environmental temperature T _C than the number 1, the environmental temperature T _C is substituted in the Expression 2, the "s" the Laplace transform as Laplace operator, the following expression 3 is obtained.

そして、τ_Ｌ＝Ｃ_Ｌ／Ｋ_Ｌ、τ_Ｅ＝Ｃ_Ｅ／Ｋ_Ｅ、η＝Ｋ_Ｘ／Ｋ_ＬをそれぞれモータコイルとＥＣＵの熱時定数とすると、下記数４が成立する。

When τ _L = C _L / K _L , τ _E = C _E / K _E , and η = K _X / K _L are the thermal time constants of the motor coil and the ECU, respectively, the following equation 4 is established.

上記数４より、例えばＡ相のモータコイル温度Ｔ_Ａを推定する温度推定モデルの構成は図２に示すようになる。即ち、Ａ相のモータ電流値ｉ_Ａの平方値は、コイルの放熱係数Ｋ_Ｌ及びＡ相抵抗Ｒ_Ａの係数ブロック１０１を経て減算部１０３に加算入力され、３相のモータ電流値ｉ_Ａ，ｉ_Ｂ，ｉ_Ｃの各平方値の和は、ＥＣＵ発熱等価抵抗Ｒ_Ｅ及び放熱係数Ｋ_Ｅの係数ブロック１０２を経て減算部１０３に減算入力される。減算部１０３で求められる差分は、熱時定数τ_Ｌの１次遅れ関数部１１１を経て加算部１２０に加算され、加算部１２０には温度ブロック１１０からＡ相初期温度Ｔ_Ａ０が加算されている。

From Equation 4, for example, configuration of the temperature estimation model for estimating the motor coil temperature T _A of the A-phase is shown in FIG. That is, the square value of the motor current i _A of the A-phase, via the coefficient block 101 for the radiation coefficients K _L and the A-phase resistance R _A of the coil are added input to the subtraction unit 103, the 3-phase motor current values i _A, The sum of the square values of i _B and i _C is subtracted and input to the subtraction unit 103 via the ECU heat generation equivalent resistance R _E and the coefficient block 102 of the heat dissipation coefficient K _E. The difference obtained by the subtracting unit 103 is added to the adding unit 120 via the first-order lag function unit 111 of the thermal time constant τ _L , and the A-phase initial temperature T _A0 is added from the temperature block 110 to the adding unit 120. .

Here, the sum of the square values of the three-phase motor current values i _A , i _B , and i _C is input to the coefficient block 102, and the square value of the A-phase motor current values i _A is input to the coefficient block 101. However, a correlated current command value (Iref3) can also be used.

Further, the temperature rise value of the B-phase and C-phase [Delta] T _B and [Delta] T _C is added by the adder 104, twice the temperature rise value [Delta] T _A of the A-phase is subtracted input to subtraction section 104, addition and subtraction portion 104 The addition / subtraction result is added to the addition unit 121 through the first-order lag function unit 113 of the thermal time constant τ _L with η (= K _X / K _L ) as a gain. The ECU temperature increase value ΔT _E is input to the adding unit 121 via the first-order phase-lag advance function unit 112 of the thermal time constants τ _L and τ _E , and the addition result in the adding unit 121 is added by the adding unit 120. The added value of the unit 120 is output as the estimated temperature TA of the _A- phase coil. That is, the sum of the added value of the output and the adding unit 121 of the first-order lag function unit 111 is a temperature rise value [Delta] T _A of the A-phase, A-phase initial temperature T _A0 to a temperature rise value [Delta] T _A as the following equation 5 by adding, it is possible to obtain the motor temperature T _a of the a-phase.
(Equation 5)
T _A = ΔT _A + T _A0

Note that the coil heat dissipation coefficient K _L , the thermal time constant τ _L , and the proportional value η vary with the motor rotation speed ω as a function of the motor rotation speed ω. Further, the A-phase resistance _{R A} modified by the A-phase estimated temperature _{T A,} ECU equivalent resistance _{R E} is corrected by ECU temperature _{T E.}

Although Figure 2 shows an example of a temperature estimation model for outputting the estimated temperature T _A of the A-phase coil, for the estimated temperature T _C of the estimated temperature T _B and C phase coils of the B-phase coil, the temperature by a similar construction An estimation model can be configured, and the temperature estimation apparatus 100 that outputs the motor coil temperature T _N (N = A, B, C) is formed by merging the A to C phase temperature estimation models.

Each coefficient described above is a value identified by data such as current and temperature measured while changing the motor rotation speed ω. For example, the coefficient is identified while increasing the motor rotation speed ω by 300 rpm. When the temperature estimated by the actual rotational speed, the radiation coefficient K _L as shown in FIG. 3 for example it can be obtained by interpolation.

Moreover, each phase resistance of the motor _{R N (N = A, B} , C), each phase inductance _{L N (N = A, B} , C) since parameters such as changes with temperature, by the following Expression 6 and number 7 Correction is performed at each temperature T. In this example, the standard room temperature is 20 ° C., but the setting of the standard room temperature is arbitrary.
(Equation 6)
R _N = R _r (1 + R _R1 × (T−T ₂₀ ))
However, Rr is a rated resistance, R _R1 is a temperature coefficient of resistance, and T ₂₀ is a standard room temperature of 20 ° C.

(Equation 7)
L _N = L _r (1 + R _L1 × (T−T ₂₀ ))
However, Lr is a rated inductance and R _L1 is a temperature coefficient of the inductance.

The estimated phase temperatures T _A , T _B , and T _C estimated and output as described above are input to the overheat protection means 200 and the output restriction means 202, and the overheat protection means 200 and the output restriction means 202 are each estimated phase temperature T _{When A 1} , T _B , or T _C exceeds the threshold, the steering assist command value Iref1 or Iref3 is limited or the motor output is limited for overheat protection.

Next, an embodiment of estimating the magnet temperature T _M of the multi-phase motor 20 (second embodiment). Magnet temperature T _M is the same deployment and coil temperature T _N, the magnet is so is one, it is possible to configure the motor temperature estimation device 100 at a single temperature estimation model.

4 shows a configuration example of a temperature estimating device 100 for estimating a magnet temperature T _M, 3-phase current values i _A, i _B, the sum of the squared values of i _C is the coil resistance R _L and the motor rotation is added input to the subtraction unit 132 via the coefficient block 130 of the heat radiation coefficient _{K M} to the outside air environment the speed ω as a function, three-phase current values _{i a,} i B, the sum of the squared values of _{i C} is, ECU fever Subtraction is input to the subtraction unit 132 through the coefficient block 131 of the equivalent resistance R _E and the heat dissipation coefficient K _E. The difference obtained by the subtracting unit 132 is added to the adding unit 136 via the first-order lag function unit 134 of the thermal time constant τ _M (= heat capacity C _{M of the} magnet / heat radiation coefficient K _M ). From 133, the magnet initial temperature _TM0 is added.

Further, the ECU temperature increase value ΔT _E is input to the adding unit 136 via the first-order phase-lag advance function unit 135 of the thermal time constants τ _E and τ _M , and the added value of the adding unit 136 is used as the magnet estimated temperature T _M. Is output. The coil resistance R _L is corrected by the magnet estimated temperature T _M , and the ECU heat generation equivalent resistance R _E is corrected by the ECU temperature T _E.

Since there is a change in the counter electromotive voltage coefficient by the temperature rise of the motor, it modifies the counter electromotive voltage coefficient K _e according to the following equation 8 by the estimated motor magnets estimated temperature T _M.
(Equation 8)
K _e (T) = K _e (T ₂₀ ) (1 + R _ket × (T _M −T ₂₀ ))
However, K _e (T) is a counter electromotive voltage coefficient under the current temperature, K _e (T ₂₀ ) is a counter electromotive voltage coefficient at a standard room temperature of 20 ° C., and R _ket is a temperature coefficient of the counter electromotive voltage coefficient.

The torque coefficient K _t (T) can be similarly corrected. That is, the correction is made by the following equation (9).
(Equation 9)
_{K t (T) = K t} (T 20) (1 + R ket × (T M -T 20))

The coefficient blocks 130 and 131 of the temperature estimation apparatus shown in FIG. 4 both input the square values of the three-phase current values i _A , i _B , and i _C , and the coefficient blocks 130 and 131 and the subtraction unit 132 are combined into one. In summary, the configuration shown in FIG. 5 can be obtained. Combined resistance coefficient R1 _L in coefficient block 137, synthetic radiation coefficient K1 _M is corrected by the motor magnets estimated temperature _{T M} or ECU temperature _{T E,} the output value of the coefficient block 137 is input to the first-order lag function unit 134.

  In the above description, an example in which the temperature estimation device is mounted on the electric power steering device is shown. Therefore, the temperature sensor detects the ECU substrate temperature, but it is only necessary to detect the motor controller (control unit) substrate temperature. In addition, the motor has three-phase examples, and the case where the coil temperatures of the A, B, and C phases are estimated has been described. However, the present invention can be applied in the same manner to motors of other phases.

It is a block diagram which shows the structural example which mounts the temperature estimation apparatus which concerns on this invention in the electric power steering apparatus. It is a block diagram showing a configuration example of a temperature estimation model for estimating the temperature T _A of the A-phase coil (first embodiment). It is a diagram showing a characteristic example for the motor rotation speed ω of the radiation coefficient K _L. It is a block diagram showing a configuration example of a temperature estimation device for estimating a magnet temperature T _M (second embodiment). It is a block diagram showing another configuration example of a temperature estimating device (second embodiment) that estimates the magnet temperature T _M. It is a figure which shows the structural example of the conventional steering device. It is a block diagram which shows the structural example of the control unit of the conventional steering apparatus. It is a connection diagram which shows the structural example of a motor drive part.

Explanation of symbols

1 Handle 2 Column shaft 10 Torque sensor 12 Vehicle speed sensor 20 Motor (M)
30 Control unit 31 Steering assist command value calculation unit 32 Phase compensation unit 36 PI control unit 37 PWM control unit 38 Inverter 100 Temperature estimation device 101, 102 Coefficient block 110 Temperature block 111, 113 First order lag function unit 112, 135 First order Phase lag advance function unit 130, 131, 137 Coefficient block 134 First-order lag function unit 200 Overheat protection means 201 Temperature sensor 202 Output limiting means

Claims (7)

The detection temperature is input from a temperature sensor that detects the temperature of the control board that controls the multi-phase motor, and the heat conduction phenomenon between the arbitrary phases and the heat conduction phenomenon of the control board caused by the temperature difference of each phase coil of the multi-phase motor. Based on each phase temperature estimation model based on each phase temperature estimation model, the resistance and inductance of each phase temperature estimation model are corrected by each temperature estimation value, and each phase coil temperature of the multiphase motor is estimated. A motor temperature estimation device characterized by that. The motor temperature estimation device according to claim 1, wherein a coefficient of each phase temperature estimation model is corrected based on a rotation speed of the multiphase motor. A detection temperature is input from a temperature sensor that detects the temperature of the control board that controls the multiphase motor, and a temperature estimation model is configured based on the heat conduction phenomenon of the magnet and the control board of the multiphase motor, and the temperature estimation A motor temperature estimation device for correcting a resistance and inductance of the temperature estimation model, a torque constant and a counter electromotive voltage constant of the multiphase motor according to a temperature estimation value of the model, and estimating a magnet temperature of the multiphase motor . The motor temperature estimation device according to claim 3, wherein a coefficient of the temperature estimation model is corrected based on a rotation speed of the multiphase motor. A temperature sensor that detects the temperature of a control board that controls the multiphase motor, and a detected temperature from the temperature sensor and each phase motor current value or current command value of the multiphase motor are input, and each phase of the multiphase motor is input. Each phase temperature estimation model for estimating the temperature of each phase coil based on the heat conduction phenomenon between arbitrary phases caused by the temperature difference of the coil and the heat conduction phenomenon of the control board, A motor temperature estimation characterized by correcting the resistance and inductance of the temperature estimation model and correcting the coefficient of each phase temperature estimation model based on the rotational speed of the multiphase motor to output each phase coil temperature apparatus. A temperature sensor that detects the temperature of a control board that controls the multiphase motor, a temperature detected from the temperature sensor, and each phase motor current value or current command value of the multiphase motor are input, and a magnet of the multiphase motor and A temperature estimation model for estimating the magnet temperature of the multiphase motor based on the heat conduction phenomenon of the control board, and the resistance and inductance of the temperature estimation model, the torque constant of the multiphase motor, and the inverse according to the magnet temperature. A motor temperature estimation device that corrects an electromotive voltage constant and corrects a coefficient of the temperature estimation model based on a rotation speed of the multiphase motor to output the magnet temperature. An electric motor comprising the motor temperature estimation device according to any one of claims 1 to 6, wherein an overheat protection function and an output limiting function are executed according to an estimated temperature value of the motor temperature estimation device. Power steering device.

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