JP2005168262A - Temperature detecting device for electric motor inverter circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature detecting device for an electric motor inverter circuit that is of a simple structure and capable of detecting inverter temperature highly accurately. <P>SOLUTION: This invention relates to the temperature detecting device that detects the temperature of the electric motor inverter circuit provided with a series connection circuit of a transistor for the upper arm side and another transistor for the lower arm side on each phase of a three-phase synchronous motor and with a parasitic diode on each transistor. A forward voltage of the parasitic diode and a current flowing in the parasitic diode are detected. These values of the detected forward voltage and the current flowing in the parasitic diode are applied to a prescribed operational expression to detect the temperature of the transistors and thereby the temperature of the inverter. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a temperature detection device that detects the temperature of an inverter circuit used when driving an electric motor.

In an inverter used to drive an electric motor, a temperature detector is disposed in the vicinity of the inverter housing in order to detect a temperature abnormality of a switching element included in the inverter, and the temperature detected by the temperature detector is When the temperature exceeds a predetermined temperature, the switching element is protected by limiting the motor torque. (For example, refer to JP-A-11-341884)
Japanese Patent Laid-Open No. 11-341884

  The temperature detector used in such an inverter is desirably provided in the vicinity of each switching element in order to detect the temperature of the switching element with higher accuracy. However, when such a method is adopted, it is necessary to provide a plurality of temperature detectors, leading to an increase in cost and problems such as a complicated layout in the inverter housing.

  The present invention has been made to solve such a conventional problem, and the object of the present invention is to provide a temperature of an inverter circuit for an electric motor that can detect an inverter temperature with a simple configuration and high accuracy. It is to provide a detection device.

  In order to achieve the above object, the present invention provides a series connection circuit of an upper arm side switching element and a lower arm side switching element for each phase of the motor, and for a motor having a parasitic diode for each switching element. The temperature detection device for detecting the inverter circuit has voltage detection means for detecting a forward voltage of the parasitic diode.

  Further, a diode current detection means for detecting a current flowing through the parasitic diode, at least a forward voltage detected by the voltage detection means, and a current detected by the current detection means, Temperature detecting means for detecting temperature.

  In the temperature detection apparatus for an inverter circuit for an electric motor according to the present invention, the parasitic voltage is detected based on the forward voltage of the parasitic diode detected by the voltage detection means and the current flowing in the parasitic diode detected by the current detection means. Since the temperature of the diode and thus the temperature of the switching element can be obtained, the temperature of the inverter circuit can be detected with a very simple configuration without mounting a large-scale temperature detector as in the prior art. Further, since temperature detection can be performed for each parasitic diode, temperature detection can be performed with extremely high accuracy based on temperature data for each switching element.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a current control system for a three-phase synchronous motor to which a temperature detection device for an inverter circuit for an electric motor according to an embodiment of the present invention is applied.

  As shown in the figure, this current control system controls the rotational drive by adjusting the current flowing through the three-phase synchronous motor (electric motor; 138), and includes three upper arm sides and a lower arm. Inverter (011) having a total of six transistors (IGBT or MOS-FET, etc .; switching elements) on the three sides (upper arm and lower arm will be described later), and driving each transistor included in the inverter (011) A transistor driver (100) to be controlled, and current sensors (135 to 137) for detecting current values iu, iv and iw flowing in the U-phase, V-phase and W-phase flowing in the three-phase synchronous motor (138). A polarity determination unit (current polarity detection means; 1) for determining the polarity of the current based on the current values iu, iv, iw detected by the current sensors (135-137) And includes 1), the.

  Further, based on the output signals of the transistor driver (100), the inverter (011), and the polarity determiner (131), the temperature of each transistor included in the inverter (011) is monitored, and the temperature is lower than a predetermined temperature. When it is determined that the temperature is high, a temperature monitor (125) that outputs an output restriction signal twa and an angle detection sensor (012) that detects the rotation angle of the three-phase synchronous motor (138) are provided.

  The polarity determiner (131) generates a U-phase polarity determination signal spnu, a V-phase polarity determination signal spnv, and a W-phase polarity determination signal spnw based on the current values iu, iv, and iw. Each signal is output to a temperature monitor (125) and a PWM controller (010) described later.

  The temperature monitor (125) includes polarity determination signals spnu, spnv, spnw output from the polarity determiner (131), and current values iu, iv, iw flowing through the three-phase synchronous motor (138), and U phase, V The temperature of each transistor of the inverter (011) is monitored based on the voltage values vu, vv, vw of the phase and W phase and a voltage command signal output from the PWM control unit (010) described later, and the detected temperature Is determined to be higher than the predetermined temperature, an output restriction signal twa is output.

The transistor driver (100) uses the information on the reference phase angle θre obtained from the angle detection sensor (012) for the three-phase alternating current values iu, iv, iw detected by the current sensors (135-137). And a three-phase / two-phase DC converter (015) that performs three-phase / two-phase conversion and outputs two-phase DC current values id and iq. This three-phase AC to two-phase DC converter (015) calculates DC current values id and iq using the following equation (1).

  Further, the current values id and iq obtained by the three-phase AC to two-phase DC converter (015), the d-axis direction current command value id * given as the two-phase current command value, and the q-axis direction current command. Based on the value iq *, a current PI control unit (003) is provided that generates a voltage command value vd * in the d-axis direction and a voltage command value vq * in the q-axis direction by proportional-integral control.

  Further, based on the reference phase angle θre obtained from the angle detection sensor (012), the phase angle correction unit (017) for obtaining the command phase angle θre *, the command phase angle θre *, and the voltage command values vd *, vq 2-phase / 3-phase AC converter (2 phase / 3 phase AC converter) to obtain U phase voltage command value vu *, V phase voltage command value vv *, and W phase voltage command value vw * based on * 006). Here, the command phase angle θre * is a phase angle at the time when the two-phase DC to three-phase AC converter (006) outputs a voltage command value.

Then, the two-phase DC to three-phase AC converter (006) calculates the three-phase voltage command values vu *, vv *, vw * using the following equation (2).

  Further, the voltage command values vu *, vv *, vw * obtained by the above equation (2), the polarity determination signals spnu, spnv, spnw output from the polarity determination unit (131), and the temperature monitor ( 125) Based on the output limit signal twa output from 125), voltage command signals (sup, sudm, svup, svdm, swup, swdm) for driving the six transistors of the inverter (011) are generated and output. A PWM controller (010) is provided.

  FIG. 2 is a circuit diagram showing a detailed configuration of the inverter (011) shown in FIG. As shown in the figure, the inverter (011) is a transistor trup that is the upper arm of the U phase, a transistor trdm that is the lower arm of the U phase, a transistor trvup that is the upper arm of the V phase, and a lower arm of the V phase. Six transistors (IGBT, MOS-FET, etc.) are provided, which are a transistor trvdm, a transistor trwup that is an upper arm of the W phase, and a transistor trwdm that is a lower arm of the W phase. 2 shows a current detector (diode current detecting means; 130) that detects a current value from the output signal of each current sensor (135 to 137) omitted in FIG.

  The transistors trup and trdm are connected in series, trup is connected to the positive direct current power supply line vdc (+), and true is connected to the negative direct current power supply line vdc (−). The control input terminal of the transistor trup is connected to the PWM controller (010) and supplied with the voltage command signal suup. Similarly, the control input terminal of the transistor trdm is connected to the PWM controller (010) and supplied with the voltage command signal sudm. The connection point between the transistors trup and trdm is connected to the U-phase input terminal of the three-phase synchronous motor (138) and also to the temperature monitor (125). Thereby, the voltage vu supplied to the U-phase is supplied to the temperature monitor (125).

  Further, the transistor trup has a parasitic diode duup, and similarly the transistor trdm has a parasitic diode dudm.

  The V-phase transistor trvup has a parasitic diode dvup, the trvdm has a parasitic diode dvdm, the W-phase transistor trwup has a parasitic diode dwup, and the trwdm has a parasitic diode dwdm. The V-phase transistors trvup and trvdm and the W-phase transistors trwup and trwdm have the same connection relationship as the above-described U-phase transistor, and thus detailed description of the connection relationship is omitted.

  FIG. 3 is a block diagram showing a detailed configuration of a temperature monitor (125) as a temperature detection device of the inverter circuit for an electric motor according to the present embodiment. In the figure, only the processing system related to the U phase is shown as a representative. Accordingly, the same processing system is actually provided for the V phase and the W phase.

  As shown in FIG. 3, the temperature monitor (125) includes an analog multiplexer (316), a voltage detector (voltage detection means; 300), a map (312), a multiplier (302), and a comparator ( 304), rising edge detectors (310) and (311), a selector (314), and a latch device (306).

  The analog multiplexer (316) receives the signals of the power supply lines vdc (+) and vdc (−) and the polarity determination signal spnu. When the polarity determination signal spnu is positive, the negative side DC power supply line vdc ( When the polarity determination signal spnu is negative, the signal of the positive DC power supply line vdc (+) is output as the output signal mul.

  The voltage detector (300) receives the voltage vu of the U-phase line and the signal mul output from the analog multiplexer (316), and obtains potential differences ΔVf1 and ΔVf2 to be described later based on the input signals. This is output as a signal vuo.

  The map (312) maps and stores the relationship between the U-phase current iu and the transistor temperature T. Based on the input U-phase current iu, the electron elementary quantity q, the Boltzmann constant k, and the reverse saturation current of the transistor are stored. By using this, the signal lniu is output. A method for calculating the signal lnuu will be described later.

  The multiplier (302) receives the output signal lniu of the map (312) and the output signal vuo of the voltage detector (300), calculates a multiplication value (vuo) × (lniu), and calculates the calculation result of the transistor. Output as a signal vut indicating the absolute temperature. That is, the map (312) and the multiplier (302) correspond to the temperature detecting means described in the claims.

  The comparator (304) inputs the signal vut output from the multiplier (302) and the transistor temperature abnormality determination value tth and compares them, and as a result, the transistor temperature exceeds the temperature abnormality determination value tth. If it is determined that the error has occurred, an abnormality detection signal tig is output.

  The falling edge detector (310) inputs the voltage command signal sup to the P side (upper arm side) transistor trup, and outputs a falling edge detection signal sup when the falling of this signal is detected. . The falling edge detector (311) inputs the voltage command signal sudm to the N side (lower arm side) transistor trdm, and when the falling edge of this signal is detected, the falling edge detection signal sudme is output. Output.

  The selector (314) receives the polarity determination signal spnu and the falling detection signals supe and sudme output from the falling edge detectors (310) and (311), and the polarity of the U-phase current iu is positive. Outputs a falling edge detection signal supe, and if negative, performs a selection process to output a falling edge detection signal sudme, and outputs the selected signal as a lac signal.

  The latch unit (306) receives the output signal tig of the comparator (304) and the lac signal output from the selector (314), latches the signal tig at each falling edge of the lac signal, and obtains a signal Is output to the transistor driver (100) as an output limiting signal twa.

  Next, the operation of the inverter (011) and the temperature detection operation in the temperature monitor (125) will be described. FIG. 4 is an explanatory diagram showing the current flowing through the series connection circuit of the U-phase transistors trup and trdm when the U-phase current is positive, and FIG. 5 shows the voltage command signals suup, sudm, and It is a timing chart which shows change of voltage vun between the neutral point of U phase and a three phase synchronous motor (138).

  When the polarity of the U-phase current is positive, that is, when a current is flowing from the transistor side to the motor side as indicated by symbol Y1 or Y2 in FIG. 4, the P-side (upper arm side) transistor trup The P-side transistor trup is turned on and the voltage vun is vun1 only during the T1 period (see FIG. 5) during which the voltage command signal suup is outputting the on command signal. At this time, the U-phase current iu flows from the positive DC power supply line vdc (+) to the U-phase electrode of the three-phase synchronous motor (138) via the P-side transistor trup (arrow Y1).

  Next, when the voltage command signal suup changes from on to off, the P-side transistor trup switches from the on-state to the off-state, and after a predetermined dead time T2 has elapsed, the voltage command of the N-side (lower arm side) transistor trdm The signal sudm is an on command. As a result, the N-side transistor trdm is turned on.

  At this time, the voltage vun changes from vun1 to vun2, and the U-phase current iu is supplied from the load DC power supply line vdc (−) via the parasitic diode dudm added to the N-side transistor trdm. It flows to the U-phase electrode of (138) (arrow Y2).

  Then, the N-side transistor “trudm” is turned on by the ON control signal of the voltage command signal “sudm” only during the period T3 during which the voltage command signal “sudm” is outputting the on command. During this T3 period, the voltage vun maintains vun2, and the U-phase current iu passes from the load DC power supply line vdc (−) to the U-phase electrode of the three-phase synchronous motor (138) via the N-side parasitic diode dudm. And flow.

  Thereafter, when the voltage command signal sudm of the N-side transistor trdm changes from on to off, the N-side transistor trdm switches from the on state to the off state, and after a predetermined dead time T4 has elapsed, the voltage command signal of the P-side transistor trup “sup” is an ON command, and the P-side transistor “trup” is turned on. Even during the dead time T4, the voltage vun is vun2, and the U-phase current iu is synchronized with the three-phase via the diode dudm parasitic to the N-side transistor trdm from the negative-side DC power supply line vdc (−). It flows to the U-phase electrode of the motor (138).

  That is, the value of the voltage vun is vun2 in both the dead time T2 when the voltage command signal suup switches from on to off and the dead time T4 when the voltage command signal sudm switches from on to off.

  Here, since the voltage vun2 described above is a forward voltage of the parasitic diode dudm, the voltage is offset by ΔVf1 with respect to the potential of (−1/2) × vdc (−). The relationship with the absolute temperature T of the diode dudm is expressed by the following equation (3).

ΔVf1 = k × (T / q) × ln (iu / Is) (3)
Where q is the elementary electron quantity, k is the Boltzmann constant, Is is the reverse saturation current of the transistor, and ln is a logarithmic symbol.

  Next, referring to FIGS. 6 and 7, when the polarity of the U-phase current is negative, that is, from the three-phase synchronous motor (138) side to the transistor side as shown by the arrow Y3 or Y4 in FIG. A case where current flows will be described.

  In this case, while the voltage command signal sup of the P side (upper arm side) transistor trup outputs the on command signal, that is, during the period T5 shown in FIG. 7, the P side transistor trup is turned on and the U phase And the neutral point of the three-phase synchronous motor (138) is vun3, and the U-phase current iu is a parasitic diode added to the P-side transistor trup from the U-phase of the three-phase synchronous motor (138). It flows to the positive DC power supply line vdc (+) through the dup (arrow Y3).

  Next, when the voltage command signal sup of the P-side transistor trup changes from the on command to the off command, the P-side transistor trup switches from the on state to the off state, and after a predetermined dead time T6 has elapsed, the N side (lower Arm side) The voltage command signal sudm of the transistor trdm is turned on, and the N side transistor trdm is turned on.

  Also during this dead time T6, the voltage vun between the U phase and the neutral point of the three-phase synchronous motor (138) maintains vun3, and the U-phase current iu is from the U phase of the three-phase synchronous motor (138). The current flows to the positive DC power supply line vdc (+) via the parasitic diode dup added to the P-side transistor trup.

  When the dead time T6 elapses, the N-side transistor trdm is turned on only during the period T7 during which the voltage command signal sudm of the N-side transistor trdm outputs an on-command signal. At this time, the voltage vun between the U-phase and the neutral point of the three-phase synchronous motor (138) is vun4, and the U-phase current iu is supplied from the U-phase electrode of the three-phase synchronous motor (138) to the N-side transistor trdm. To the negative side DC power supply line vdc (−) (arrow Y4).

  Thereafter, when the T7 period elapses, the voltage command signal sudm of the N-side transistor trdm switches from an on command to an off command, the N-side transistor trdm turns off, and after a predetermined dead time T8, the P-side transistor trup is turned on. Become. At this time, the voltage vun between the U-phase and the neutral point is vun3, and the U-phase current iu is supplied from the U-phase of the three-phase synchronous motor (138) via the parasitic diode dup added to the P-side transistor trup. , Flows to the positive DC power supply line vdc (+).

  That is, the value of the voltage vun is vun3 in both the dead time T6 when the voltage command signal suup is switched from on to off and the dead time T8 when the voltage command signal sudm is switched from on to off.

  Here, since the voltage vun3 is a forward voltage of the parasitic diode dup, the voltage is offset by ΔVf2 with respect to the potential of (1/2) × vdc (+). Here, the offset voltage Vf2 can be calculated by the above-described equation (3). Thus, the offset voltages ΔVf1 and ΔVf2 were obtained.

  Here, the operation of the upper arm side transistor trup and the lower arm side transistor trdm for the U phase of the inverter (011) has been described. However, the same applies to the V phase and the W phase. Omitted.

  Next, the processing operation of the temperature monitor (125) shown in FIG. 3 will be described. The analog multiplexer (316) is supplied with the signal of the positive DC power supply line vdc (+) and the signal of the negative DC power supply line vdc (−), and further receives the polarity determination signal spnu from the polarity determiner (131). When given, the analog multiplexer (316) outputs vdc (−) as the output signal mul when the polarity determination signal sunp is positive, and outputs vdc (+) as the output signal when it is negative. Output as mul.

  The voltage detector (300) is supplied with the U-phase line voltage signal vu and the output signal mul, and subtracts them to calculate the offset voltages ΔVf1 and ΔVf2 (see FIGS. 5 and 7). The calculation result is output as a signal vuo.

  On the other hand, in the map (312), the value of luiu represented by the following equation (4) is mapped and stored.

lniu = (q / k) × 1 / {ln (iu / Is)} (4)
Where q is the elementary electron quantity, k is the Boltzmann constant, Is is the reverse saturation current of the transistor, and ln is a logarithmic symbol. The equation (4) can be easily obtained by dividing both sides of the above-described equation (3) by the absolute temperature T and taking the reciprocal. That is, lnuu = T / ΔVf1.

  Then, when the U-phase current iu is input to the map (312), lniu is obtained based on the above equation (4), and this output signal lniu is supplied to the multiplier (302). The multiplier (302) multiplies the signal lniu and the signal vuo output from the voltage detector (300). Here, since the signal vuo output from the voltage detector (300) is the offset voltages ΔVf1 and ΔVf2 as described above, the multiplication result vut becomes the absolute temperature T of the parasitic diode duup or dudm. The signal vut is output to the comparator (304).

  Next, the comparator (304) compares the signal vut supplied from the multiplier (302) with a predetermined determination value tth indicating temperature abnormality, and when the signal vut exceeds the determination value tth, abnormality detection is performed. The signal tig is output to the latch device (306).

  On the other hand, based on the polarity determination signal spnu of the U-phase current, the selector (314) receives the falling edge detection signal “supple” provided from the falling edge detector (310) when the polarity of the U-phase current is positive. When the polarity of the U-phase current is negative, the falling edge detection signal sudme supplied from the falling edge detector (311) is output as the lag signal.

  The latch unit (306) latches the signal tig at each falling edge of the lac signal, and outputs the latched signal to the PWM controller (010) as the output limit signal twa.

  Thus, when the temperature of the parasitic diode rises above a predetermined temperature, the output limit signal twa is output from the temperature monitor (125), and the output limit signal twa is given to the PWM controller (010). The current output supplied to the three-phase synchronous motor (138) is limited, and the temperature rise of the inverter circuit can be suppressed.

  The above operation will be described below with reference to the timing chart shown in FIG. The left side from the center of the figure shows the case where the polarity of the U-phase current is positive, and the right side shows the case where the polarity of the U-phase current is negative. That is, the current polarity signal spnu shown in FIG. 4A is positive on the left side and negative on the right side.

  When the current polarity signal spnu is positive, the signal of the negative side DC power supply line vdc (−) is output as the output signal mul of the analog multiplexer (316) shown in FIG. On the other hand, when the current polarity signal spnu is negative, the signal of the positive DC power supply line vdc (+) is output.

  Also, as shown in FIGS. 3C and 3D, the voltage command signals sup and sudm are output as mutually contradictory signals. When sup is on, sudm is off, and when sup is off, sudm is on. Become.

  When spnu is positive, the voltage vun shown in FIG. 5E is switched between the voltages vun1 and vun2 in synchronization with the fall and rise of the voltage command signal suup as shown in FIG. A latch signal is output from the selector (314) shown in FIG. 3 at the time of the fall of the supply, that is, at the timings t1, t2, and t3 shown in FIG. 8 (f).

  When the temperature of the transistor rises with time, the signal vuo corresponding to the offset voltage Vf1 rises as shown in FIG. 5G, and the multiplier (302) as shown in FIG. ) Output signal vut (absolute temperature T signal) increases. Then, when the signal vut indicating the absolute temperature exceeds a predetermined determination value tth and then the lac signal is given, the output limit signal twa is output from the latch device (306) as shown in FIG. Time t4). Since this output limit signal twa is supplied to the PWM controller (010) shown in FIG. 1, the PWM controller (010) controls the current value supplied to the three-phase synchronous motor (138). Thus, control is performed to reduce the temperature rise of the transistor. The same applies to the case where the current polarity signal spnu is negative (in the case of the right side in FIG. 8), and the description thereof is omitted.

  Thus, in the temperature detection device for an inverter circuit for an electric motor according to the present embodiment, the current value flowing through the parasitic diode added to the transistor constituting the inverter (011) is detected, and based on this current value, Since the temperature of the parasitic diode is obtained, the temperature of the inverter circuit can be detected with a very simple configuration and with high accuracy.

  That is, based on the forward voltage of the parasitic diode detected by the voltage detection means and the current flowing through the parasitic diode detected by the current detection means, the temperature of the parasitic diode and hence the temperature of the switching element is obtained. Therefore, the temperature of the inverter circuit can be detected with a very simple configuration without mounting a large-scale temperature detector as in the prior art. Further, since temperature detection can be performed for each parasitic diode, temperature detection can be performed with extremely high accuracy based on temperature data for each switching element.

  Further, since the map (312) stores map data corresponding to the arithmetic expression shown in the above equation (4), when the current value iu is given, the corresponding output signal lniu (= T / ΔVf1) can be obtained immediately without performing complicated arithmetic processing. Furthermore, by multiplying this signal lnuu by the signal vuo (= ΔVf1) obtained by the voltage detector (300), the absolute value of the transistor can be obtained. Since the temperature T is obtained, the calculation process can be simplified, the calculation process time can be shortened, and the detection accuracy can be increased.

  That is, the current i flowing through the parasitic diode, and the forward voltage of the parasitic diode and the offset voltage ΔV of the power supply voltage are detected, and the temperature of the switching element is detected by a predetermined arithmetic expression based on these data. Accuracy can be improved. Further, by mapping the arithmetic expression, the arithmetic processing can be simplified, and the processing time can be shortened.

  Further, when the current flowing through the transistor is directed from the inverter (011) to the three-phase synchronous motor (138), the temperature of the transistor on the lower arm side is measured, and on the contrary, the three-phase synchronous motor is measured. When the direction from (138) is directed to the inverter (011), the temperature of the transistor on the upper arm side is measured, so that suitable temperature detection according to the direction of the current can be performed.

  That is, when the current flowing through the switching element is from the inverter to the motor, the temperature of the transistor on the lower arm side is measured, and when the current is flowing from the motor to the inverter, the transistor on the upper arm side is measured. Since temperature is measured, suitable temperature detection according to the direction of electric current is attained.

  As mentioned above, although the temperature detection apparatus of the inverter circuit for electric motors of this invention was demonstrated based on embodiment of illustration, this invention is not limited to this, The structure of each part is arbitrary structures which have the same function Can be replaced.

  For example, in the above-described embodiment, an example has been described in which a map corresponding to the arithmetic expression shown in Expression (4) is created and this map is stored. However, the present invention is not limited to this and the arithmetic operation is not limited thereto. It is also possible to store only the formula and perform the calculation process every time data is given.

  This is extremely useful for detecting the temperature of an inverter used in an electric motor.

It is a block diagram which shows the structure of the current control system of the three-phase synchronous motor to which the temperature detection apparatus which concerns on one Embodiment of this invention is applied. FIG. 2 is a circuit diagram showing a detailed configuration of the inverter shown in FIG. 1. It is a block diagram which shows the detailed structure of the temperature monitor shown in FIG. It is explanatory drawing which shows the flow of an electric current when the connection state and current polarity of the U-phase transistor provided in an inverter are positive. 7 is a timing chart showing changes in voltage command signals sup, sudm and voltage vun when a positive current flows through a U-phase transistor. It is explanatory drawing which shows the flow of an electric current when the connection state of a U-phase transistor provided in an inverter and a current polarity are negative. 6 is a timing chart showing changes in voltage command signals sup, sudm and voltage vun when a negative current flows through a U-phase transistor. It is a timing chart which shows operation | movement of the temperature detection apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

003 Current PI control unit 006 2 phase DC 3 phase AC converter 010 PWM controller 011 Inverter 012 Angle detection sensor 015 3 phase AC 2 phase DC converter 017 Phase angle correction unit 100 Transistor driver 125 Temperature monitor 130 Current detector (Diode current detection means)
131 Polarity determination device (current polarity determination means)
135, 136, 137 Current sensor 138 Three-phase synchronous motor (electric motor)
300 Voltage detector (voltage detection means)
302 Multiplier 304 Comparator 306 Latcher 310, 311 Rising edge detector 312 Map 314 Selector 316 Analog multiplexer

Claims (3)

In the temperature detection device for detecting a series connection circuit of the upper arm side switching element and the lower arm side switching element for each phase of the electric motor and detecting the inverter circuit for the electric motor having a parasitic diode for each of the switching elements,
Voltage detecting means for detecting a forward voltage of the parasitic diode;
Diode current detection means for detecting current flowing in the parasitic diode;
Temperature detecting means for detecting the temperature of the switching element based on at least the forward voltage detected by the voltage detecting means and the current detected by the current detecting means;
A temperature detection device for an inverter circuit for an electric motor. In the temperature detection apparatus of the inverter circuit for electric motors of Claim 1,
The temperature detecting means detects the temperature T of the switching element based on the following equation, and detects the temperature of the inverter circuit for an electric motor.
ΔV = k × T / q × ln (i / Is)
Where ΔV is the forward voltage of the parasitic diode and the offset voltage of the power supply voltage
k: Boltzmann constant
q: Elementary electron content
i: current flowing in the parasitic diode Is: reverse saturation current of the transistor In the temperature detection apparatus of the inverter circuit for electric motors in any one of Claim 1 or Claim 2,
Current polarity detection means for detecting whether current is flowing from the inverter to the motor or from the motor to the inverter;
The temperature detecting means includes
When the current polarity detection means detects that a current flows from the inverter to the electric motor, the temperature of the lower arm side switching element is detected, and the electric current flows from the electric motor to the inverter. When this is detected, the temperature detection device for an inverter circuit for an electric motor detects the temperature of the upper arm side switching element.

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