JP4445821B2 - Current polarity detection circuit and semiconductor device having the same - Google Patents

Description

  The present invention relates to a current polarity detection circuit suitable for use in an inverter drive motor and a semiconductor device having the same.

In recent years, inverter-controlled brushless motors have been widely adopted as motors for household electric appliances. A brushless motor is usually provided with a position sensor such as a Hall element or Hall IC, and is configured to apply a voltage to a coil of the motor based on position information from the position sensor. When a voltage is applied to the motor coil, a current determined by the applied voltage and the induced voltage generated in the coil flows through the coil. The magnitude of the induced voltage varies depending on the rotation speed of the motor. Therefore, when a voltage is applied at a certain timing based on position information from the position sensor, the phase of the current flowing through the coil changes depending on the rotation speed . If the phase of the induced voltage is shifted from the phase of the current, the power factor is lowered, and the efficiency of the motor is lowered. In order to prevent this, it is necessary to perform phase control for matching the current phase and the induced voltage phase. The current phase can be detected by monitoring the motor current with a current sensor. However, current sensors for motors are expensive and cannot be used in household electrical equipment.

  Japanese Patent Application Laid-Open Nos. 10-285982 and 10-341588 describe a method for detecting the polarity of a motor current without using a current sensor.

  A current polarity detection circuit described in Japanese Patent Laid-Open No. 10-285982 will be described with reference to FIGS. As shown in FIG. 10, the inverter device includes an upper arm switching element T1, a lower arm switching element T4, and driving circuits K1, K4 for driving the switching elements T1, T4. The coil terminal of the motor M1 is connected to the midpoint of the switching elements T1 and T4. Free-wheeling diodes D1 and D4 are connected in antiparallel to the switching elements T1 and T4. A resistor R3 is connected to the lower arm switching element T4.

  The current polarity detection circuit includes a comparator C2 and a latch circuit F2. The comparator C2 determines whether the voltage VUR of the resistor R3 is positive or negative. The latch circuit F2 inverts the comparator output signal VUC at the falling timing of the lower arm control signal VUB and outputs it as a current polarity signal VUP. The latch circuit F2 holds the previous signal until the next timing when the lower arm control signal VUB falls.

  In this example, when the upper arm switching element T1 is off and the lower arm switching element T4 is on, the current polarity is detected by monitoring the direction of the current flowing through the resistor R3 at the falling timing of the lower arm control signal VUB. .

The operation of the current polarity detection circuit of FIG. 10 will be described with reference to FIG. 11A shows the upper arm control signal VUT, and FIG. 11B shows the lower arm control signal VUB. 11C shows the operation of the upper arm switching element T1, and FIG. 11D shows the operation of the lower arm switching element T4. H is on and L is off. FIG. 11E shows the motor current IUM. The motor current IUM is a current that flows into the motor. The polarity is positive when the current flows toward the motor, and the polarity is negative when the current flows from the motor. 11F shows the voltage VUR of the resistor R3, FIG. 11G shows the output voltage VUC of the comparator C2, and FIG. 11H shows the output voltage VUP of the latch circuit F2. FIG. 11I shows the timing of monitoring the current, that is, the timing at which the latch circuit F2 latches the output voltage VUC of the comparator C2.

  Comparing FIG. 11A and FIG. 11B, a section (dead time) in which the upper arm control signal VUT and the lower arm control signal VUB are simultaneously turned off is provided. This is provided to prevent the upper and lower arm switching elements from being turned on simultaneously.

  As shown in FIG. 11I, the timing for monitoring the current is the time points t1, t2, t3, and t4 when the lower arm control signal VUB falls from “H” to “L”. As can be seen by comparing FIG. 11B and FIG. 11D, the operation of the lower arm switching element T4 is slightly delayed with respect to the lower arm control signal VUB. Therefore, at the timing t1 when the lower arm control signal VUB falls from “H” to “L”, the upper arm switching element T1 is off as shown in FIG. 11C, but the lower arm switching element T4 as shown in FIG. 11D. Is still on.

  When the motor current IUM in FIG. 11E is negative, that is, at time points t1 and t2, as shown in FIG. 11D, the lower arm switching element T4 is on, and the current flows from the motor via the lower arm switching element T4 and the resistor R3. It flows to GND. Therefore, as shown in FIG. 11F, the voltage VUR of the resistor R3 becomes positive.

  When the motor current IUM in FIG. 11E is positive, that is, at time points t3 and t4, the upper arm switching element T1 is off as shown in FIG. 11C. Flow to the motor. Therefore, as shown in FIG. 11F, the voltage VUR of the resistor R3 is negative.

  The comparator output voltage VUC in FIG. 11G indicates the result of positive / negative determination of the voltage VUR of the resistor R3. When the voltage VUR of the resistor R3 is positive, the comparator output voltage VUC is “H”, and when the voltage VUR of the resistor R3 is negative, the comparator output voltage VUC is “L”.

  The current polarity signal VUP in FIG. 11H is obtained by inverting the comparator output signal VUC at the falling timing of the lower arm control signal VUB.

  Comparing FIG. 11E and FIG. 11H, when the motor current IUM changes from negative to positive, the current polarity signal VUP changes from “L” to “H”. The current polarity signal VUP changes from “L” to “H” at the time t3 when the motor current IUM changes to positive and the lower arm control signal VUB first falls.

  In this example, a resistor having a small resistance value of about 1Ω is usually used as the resistor R3. This is to prevent the gate voltage of the lower arm switching element T4 from being lowered by the voltage generated in the resistor. When the resistance value of the resistor R3 is reduced, the voltage VUR of the resistor R3 is reduced, and the comparator C2 needs to detect the polarity of a minute voltage.

12, the comparator C2 offset voltage - a timing chart showing a case having Voff. As shown in FIG. 12F, the comparator C2, a negative offset voltage - having Voff. As shown in FIG. 12G, the output voltage VUC of the comparator C2 becomes “L” only when the input voltage VUR falls below the offset voltage −Voff. Therefore, at time t3, the output voltage VUC of the comparator C2 is “H”, and becomes “L” after time t4. Accordingly, as shown in FIG. 12H, the current polarity signal VUP becomes positive at time t4.

In this example, the comparator C2 offset voltage - because of its Voff, it is impossible to detect the polarity of the current accurately.

A current polarity detection circuit described in Japanese Patent Laid-Open No. 10-341588 will be described with reference to FIGS. In the example of FIG. 13, the comparator C3 compares the output terminal voltage VUM of the inverter with the reference voltage Vref. The value of the reference voltage Vref is normally set to about ½ of the motor driving power supply voltage VDC in order to stably operate this circuit. In this example, when both the upper arm switching element T1 and the lower arm switching element T4 are off, the current polarity is detected by monitoring the output terminal voltage VUM at the rising timing of the lower arm control signal VUB.

The operation of the current polarity detection circuit of FIG. 13 will be described with reference to FIG. 14A shows the upper arm control signal VUT, and FIG. 14B shows the lower arm control signal VUB. FIG. 14C shows the operation of the upper arm switching element T1, and FIG. 14D shows the operation of the lower arm switching element T4. H is on and L is off. FIG. 14E shows the motor current IUM. The motor current IUM is a current that flows into the motor. The polarity is positive when the current flows toward the motor, and the polarity is negative when the current flows from the motor. 14F shows the output terminal voltage VUM of the inverter , FIG. 14G shows the output voltage VUC of the comparator C3, and FIG. 14H shows the output voltage VUP of the latch circuit F3. FIG. 14I shows the timing of monitoring the current, that is, the timing at which the latch circuit F3 latches the output voltage VUC of the comparator C3.

  As shown in FIG. 14I, the timing of monitoring the current is the time points t1, t2, t3, and t4 when the lower arm control signal VUB of FIG. 14B rises from “L” to “H”. As can be seen by comparing FIG. 14B and FIG. 14D, the operation of the lower arm switching element T4 is slightly delayed with respect to the lower arm control signal VUB. Therefore, at the timing t1 when the lower arm control signal VUB rises from “L” to “H”, the upper arm switching element T1 is off as shown in FIG. 14C, but the lower arm switching element T4 is also turned off as shown in FIG. 14D. Still off.

  When the motor current IUM in FIG. 14E is negative, that is, at time points t1 and t2, the current flows from the motor to the motor driving power source through the upper arm return diode D1. Therefore, as shown in FIG. 14F, the output terminal voltage VUM is substantially the motor drive power supply voltage VDC.

  When the motor current IUM in FIG. 14E is positive, that is, at time points t3 and t4, current flows from GND to the motor through the lower arm return diode D4. Therefore, as shown in FIG. 14F, the output terminal voltage VUM is almost zero.

  The comparator output voltage VUC in FIG. 14G indicates a comparison result between the output terminal voltage VUM and the reference voltage Vref. When the output terminal voltage VUM is substantially equal to the motor drive power supply voltage VDC, the comparator output voltage VUC is “H”, and when the output terminal voltage VUM is approximately 0, the comparator output voltage VUC is “L”.

  The current polarity signal VUP in FIG. 14H is obtained by inverting the comparator output signal VUC at the rising timing of the lower arm control signal VUB in FIG. 14B.

  Comparing FIG. 14E and FIG. 14H, when the motor current IUM changes from negative to positive, the current polarity signal VUP changes from “L” to “H”. The current polarity signal VUP changes from “L” to “H” at time t3 when the motor current IUM changes to positive and the lower arm control signal VUB first rises.

In this example, the comparator C3 is directly connected to the output terminal of the inverter . When the motor drive power supply voltage VDC is high, the output terminal voltage VUM is also high. Therefore, it is necessary to use a special high-voltage comparator for the comparator C3, and a general low-voltage comparator cannot be used. .

  In this example, in order to perform a stable operation, it is desirable that the reference voltage Vref is about ½ of the motor driving power supply voltage VDC. In the timing chart of FIG. 14, the reference voltage Vref is set to ½ times the motor driving power source.

  FIG. 15 shows a timing chart when the motor drive power supply voltage VDC is lowered to ½ or less without changing the setting of the reference voltage Vref. As shown in FIG. 15F, the output terminal voltage VUM is lower than the reference voltage Vref regardless of whether the motor current IUM is positive or negative. As shown in FIG. 15G, the comparator output voltage VUC is “L” regardless of whether the motor current IUM is positive or negative. As shown in FIG. 15H, the current polarity signal VUP is always “H”. Therefore, the current polarity cannot be detected accurately.

In order to avoid this, it is necessary to set the reference voltage Vref for each system having a different motor drive power supply voltage VDC. Further , in the case of a system in which the motor drive power supply voltage VDC changes greatly, it is necessary to control the reference voltage Vref according to the motor drive power supply voltage VDC.

JP-A-10-285982 Japanese Patent Laid-Open No. 10-341588

  In the example described in Japanese Patent Laid-Open No. 10-285982, the current polarity cannot be accurately detected when the comparator has the offset voltage Voff.

  In the example described in Japanese Patent Laid-Open No. 10-341588, when the motor drive power supply voltage VDC is high, a general low voltage comparator cannot be used, and when the motor drive power supply voltage VDC changes, the reference voltage is used. Vref setting operation is required.

An object of the present invention is to provide a current polarity detection circuit capable of accurately detecting the current polarity even when the motor drive power supply voltage VDC changes.

Current polarity detection circuit, the upper arm switching element and the constant-voltage circuit connected to an output terminal which is a connection point of the lower arm switching element, the upper arm switching element and the lower arm switching elements are both off timing in and a latch circuit for latching the signal, the constant voltage circuit, the voltage of the output terminal outputs an "H" signal when equal to the supply voltage substantially motor driving voltage of the output terminal is substantially zero When the motor driving power supply voltage changes within a predetermined range, the "H" signal voltage level is substantially constant regardless of the motor driving power supply voltage. The voltage level of the “L” signal is zero .

According to the present invention, even when the motor drive power supply voltage VDC changes, the current polarity can be accurately detected.

  A first example of a current polarity detection circuit according to the present invention will be described with reference to FIG. As shown in FIG. 1, the inverter device includes an upper arm switching element T1, a lower arm switching element T4, and drive circuits K1 and K4 for driving the switching elements T1 and T4. The coil terminal of the motor M1 is connected to the midpoint of the switching elements T1 and T4. Free-wheeling diodes D1 and D4 are connected in antiparallel to the switching elements T1 and T4.

  The current polarity detection circuit of this example includes a level shift circuit L1, a comparator C1, and a latch circuit F1.

The level shift circuit L1 converts the output terminal voltage VUM of the inverter to a lower voltage and outputs it. Specifically, when the output terminal voltage VUM is substantially equal to the motor drive power supply voltage VDC, a signal having a predetermined voltage level is output. Hereinafter, this is referred to as an “H” signal. When the output terminal voltage VUM is substantially zero, a zero level voltage signal is output. Hereinafter, this is referred to as an “L” signal. The comparator C1 compares the output voltage VUL of the level shift circuit with the reference voltage Vref. The value of the reference voltage Vref is set to about ½ of the voltage level of the “H” signal of the level shift circuit output voltage VUL in order to stably operate the circuit. In this example, when both the upper arm switching element T1 and the lower arm switching element T4 are off, the current polarity is determined by monitoring the output voltage VUL of the level shift circuit L1 at the rising timing of the lower arm control signal VUB. To detect.

  The latch circuit F1 inverts the comparator output signal VUC at the rising timing of the lower arm control signal VUB and outputs it as a current polarity signal VUP. The latch circuit F1 holds the previous signal until the next rise of the lower arm control signal VUB. When the current polarity detection circuit of this example is compared with the conventional current polarity detection circuit of FIG. 13, the current polarity detection circuit of this example is different in that a level shift circuit L1 is additionally provided. Only the different points will be described below.

The operation of the first example of the current polarity detection circuit of FIG. 1 will be described with reference to FIG. 2A shows the upper arm control signal VUT, and FIG. 2B shows the lower arm control signal VUB. 2C shows the operation of the upper arm switching element T1, and FIG. 2D shows the operation of the lower arm switching element T4. H is on and L is off. FIG. 2E shows the motor current IUM. The motor current IUM is a current that flows into the motor. The polarity is positive when the current flows toward the motor, and the polarity is negative when the current flows from the motor. 2F shows the output terminal voltage VUM of the inverter , FIG. 2G shows the output voltage VUL of the level shift circuit L1, FIG. 2H shows the output voltage VUC of the comparator C1, and FIG. 2I shows the output voltage VUP of the latch circuit F1. FIG. 2J shows the timing of monitoring the current, that is, the timing at which the latch circuit F1 latches the output voltage VUC of the comparator C1 .

  As shown in FIG. 2J, the current is monitored at timings t1, t2, t3, and t4 when the lower arm control signal VUB of FIG. 2B rises from “L” to “H”. As can be seen by comparing FIG. 2B and FIG. 2D, the operation of the lower arm switching element T4 is slightly delayed with respect to the lower arm control signal VUB. Therefore, at the timing t1 when the lower arm control signal VUB rises from “L” to “H”, the upper arm switching element T1 is off as shown in FIG. 2C, but the lower arm switching element T4 is also turned off as shown in FIG. 2D. Still off.

  When the motor current IUM in FIG. 2E is negative, that is, at time points t1 and t2, the current flows from the motor to the motor driving power source through the upper arm return diode D1. Therefore, as shown in FIG. 2F, the output terminal voltage VUM is substantially equal to the motor drive power supply voltage VDC.

  When the motor current IUM in FIG. 2E is positive, that is, at time points t3 and t4, current flows from GND to the motor through the lower arm freewheeling diode D4. Therefore, as shown in FIG. 2F, the output terminal voltage VUM is almost zero.

The output voltage VUL of the level shift circuit L1 in FIG. 2G is obtained by reducing the output terminal voltage VUM of the inverter in FIG. 2F. Therefore, the amplitude of the output voltage VUL is smaller than the amplitude of the output terminal voltage VUM, but the waveform is the same. The amplitude of the output voltage VUL is adjusted to be larger than the reference voltage Vref.

  The output voltage VUC of the comparator in FIG. 2H indicates a comparison result between the output voltage VUL of the level shift circuit L1 and the reference voltage Vref. When the output voltage VUL of the level shift circuit is higher than the reference voltage Vref, the output voltage VUC of the comparator is “H”, and when the output voltage VUL of the level shift circuit is lower than the reference voltage Vref, the output voltage VUC of the comparator is “L”. "

  The current polarity signal VUP in FIG. 2I is obtained by inverting the comparator output signal VUC at the rising timing of the lower arm control signal VUB in FIG. 2B.

  Comparing FIG. 2E and FIG. 2I, when the motor current IUM changes from negative to positive, the current polarity signal VUP changes from “L” to “H”. The current polarity signal VUP changes from “L” to “H” at time t3 when the motor current IUM changes to positive and the lower arm control signal VUB first rises.

According to this example, even when the motor current is small, a minute voltage is not handled, so that the current polarity can be accurately detected. In this example, the output terminal voltage VUM of the inverter is converted into a low voltage by the level shift circuit L1, and the converted voltage VUL is input to the comparator C1. Therefore, even when the motor drive power supply voltage VDC is high, a general low voltage comparator can be used as the comparator C1.

  In the first example of the current polarity detection circuit of FIG. 1, a constant voltage circuit may be used instead of the level shift circuit L1.

FIG. 3 shows the operation of the current polarity detection circuit when a constant voltage circuit is used instead of the level shift circuit L1. In this example, the motor drive power supply voltage VDC is ½ or less that in the example of FIG. Therefore, the output terminal voltage VUM of the inverter of FIG. 3F is smaller than the output terminal voltage VUM of the inverter of FIG. 2F. However, the voltage level when the constant voltage circuit output voltage VUL of FIG. 3G is “H” is the same as the voltage level when the level shift circuit output voltage VUL of FIG. 2G is “H”. Therefore, the reference voltage Vref can always be set to ½ of the “H” level of the output voltage VUL of the constant voltage circuit regardless of the motor drive power supply voltage VDC.

FIG. 7 shows an example of a constant voltage circuit. The constant voltage circuit of this example includes an NMOS transistor M1 and a resistor R1 connected in series with each other. The output terminal voltage VUM of the inverter is input from the drain of the NMOS transistor M1, and the constant voltage circuit output voltage VUL is output from the source of the NMOS transistor M1. The NMOS transistor M1 functions as a constant current circuit within a range where the current is saturated. Therefore, when the output terminal voltage VUM of the inverter is “H”, the NMOS transistor M1 causes a constant current to flow through the resistor R1, thereby setting the constant voltage circuit output voltage VUL to a constant level. A bipolar transistor may be used instead of the MOS transistor.

FIG. 8 shows another example of the constant voltage circuit. The constant voltage circuit of this example includes a resistor R2 and a Zener diode Z1 connected in series with each other. The output terminal voltage VUM of the inverter is input from one end of the resistor R2, and the constant voltage circuit output voltage VUL is output from the other end of the resistor R2. In this example, a constant voltage is output by using the Zener diode Z1.

  A second example of the current polarity detection circuit according to the present invention will be described with reference to FIG. The current polarity detection circuit of this example is different from the first example of FIG. 1 in that the comparator C1 is removed in this example. Further, the current polarity detection circuit of this example is different from the example of FIG. 13 in that a level shift circuit L1 is provided instead of the comparator C1 in this example.

In the first example of FIG. 1, when the difference between the level shift circuit output voltage VUL and the reference voltage Vref is small, the comparator C1 is required to amplify the signal. In other cases, the comparator C1 is used. You don't have to. Therefore, in this example, the comparator C1 is removed.

  FIG. 5 shows the operation of the second example of the current polarity detection circuit of the present invention. When FIG. 5 is compared with FIG. 2, FIG. 5 is different in that FIG. 5G is replaced instead of FIG. 2G and FIG. 2H, and the others are the same. FIG. 6 shows the operation of the second example of the current polarity detection circuit when a constant voltage circuit is used instead of the level shift circuit L1. 6 is different from FIG. 3 in that FIG. 6 is replaced with FIG. 6G instead of FIG. 3G and FIG. 3H, and the rest is the same.

FIG. 9 shows an example in which an inverter device using a current polarity detection circuit according to the present invention is applied to a three-phase motor speed control system . The three-phase motor speed control system includes a converter 2 that rectifies the commercial power source 1, a speed command unit 3, a position sensor 4 provided in the three-phase motor M1, and an inverter device. The inverter device includes upper arm switching elements T1, T2, T3, lower arm switching elements T4, T5, T6, driving circuits K1 to K3 and K4 to K6 for driving the switching elements T1 to T3 and T4 to T6, and current polarity. It has detection circuits P1, P2, P3 and a control unit S1. Free-wheeling diodes D1-D6 are connected in antiparallel to the switching elements T1-T6. A coil terminal of the motor M1 is connected to a midpoint between the upper arm switching element and the lower arm switching element. Each of the three phases is provided with current polarity detection circuits P1, P2, and P3 according to the present invention.

  The current polarity detection circuits P1, P2, and P3 input the output terminal voltages VUM, VVM, and VWM of the coil of the motor M1 and the lower arm control signals VUB, VVB, and VWB, and output the current polarity signals VUP, VVP, and VWP. To do.

  If the circuit shown by the broken line 1 or the broken line 2 in FIG.

  By using the semiconductor device in this way, when the motor M1 is small, the circuit of the broken line portion 2 can be built in the motor. As a method for separating each element in the semiconductor device, there are generally PN junction separation, dielectric separation (DI separation), SOI, and the like. The circuit according to the present invention can be realized in a semiconductor device using any of the separation methods.

  In addition, the current polarity detection circuit according to the present invention can be configured in a discrete manner because the circuit scale is small.

  The relationship between the voltage applied to the motor and the motor current is determined by the rotational speed of the motor. Therefore, the current polarity signal of the other phase can be estimated from a certain one-phase current polarity signal. Therefore, in FIG. 9, the current polarity detection circuit is provided for all three phases of the three-phase motor, but this may be only one phase or only two phases.

  The current polarity detection circuit according to the present invention can be used regardless of a driving method such as a sine wave driving method, a pseudo sine wave driving method, and a 120-degree energization method.

  According to the present invention, the motor efficiency can be prevented from lowering by matching the phase of the motor current and the phase of the induced voltage. The present invention can also be applied to a method of driving a motor without using a sensor such as a Hall IC, that is, a so-called sensorless driving method. A method of performing sensorless driving by the current polarity detection circuit is described in, for example, Japanese Patent Laid-Open No. 10-285982.

  The example of the present invention has been described above, but the present invention is not limited to the above-described example, and various modifications can be made by those skilled in the art within the scope of the invention described in the claims. It will be understood.

It is a figure which shows the 1st example of the current polarity detection circuit by this invention. It is a figure which shows the timing chart of the 1st example of the current polarity detection circuit by this invention of FIG. It is a figure which shows the timing chart of the modification of the 1st example of the current polarity detection circuit by this invention of FIG. It is a figure which shows the 2nd example of the current polarity detection circuit by this invention. FIG. 5 is a timing chart of a second example of the current polarity detection circuit according to the present invention in FIG. 4. FIG. 6 is a diagram showing a timing chart of a modification of the second example of the current polarity detection circuit according to the present invention in FIG. 4. It is a figure which shows the 1st example of a constant voltage circuit. It is a figure which shows the 2nd example of a constant voltage circuit. It is a figure which shows the example of the system using the current detection circuit by this invention. It is a figure which shows the 1st example of the current polarity detection circuit by a prior art. It is a figure which shows the timing chart of the 1st example of the current polarity detection circuit by the prior art of FIG. It is a figure which shows the timing chart of the modification of the 1st example of the current polarity detection circuit by the prior art of FIG. It is a figure which shows the 2nd example of the current polarity detection circuit by a prior art. It is a figure which shows the timing chart of the 2nd example of the current polarity detection circuit by the prior art of FIG. It is a figure which shows the timing chart of the modification of the 2nd example of the current polarity detection circuit by the prior art of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Commercial power supply 2; Converter 3; Speed command part 4; Position sensor T1, T2, T3; Upper arm switching element T4, T5, T6; Lower arm switching element D1, D2, D3; Upper arm return diode D4, D5, D6; Lower arm free-wheeling diodes K1, K2, K3; Upper arm driving circuit K4, K5, K6; Lower arm driving circuit M1; Motor P1, P2, P3; Current polarity detection circuit S1 ; Control circuit VUT, VVT, VWT; Upper arm control signal VUB, VVB, VWB; Lower arm control signal VUM, VVM, VWM; Output terminal voltage VUP, VVP, VWP; Current polarity signal VDC; Motor drive power supply voltage GND; Ground potential F1, F2, F3; Latch Circuits C1, C2, and C3; Comparators R1, R2, and R3; Resistance Vref; Reference voltage L1; Rushifuto circuit M1; NMOS transistor Z1; Zener diode VUC; comparator output voltage VUR; resistor R3 of the voltage VUL; level shift circuit output voltage Voff; comparator offset voltage IUM; motor current

Claims (4)

In the current polarity detection circuit for detecting the current polarity of the motor connected to the inverter device having the upper arm switching element and the lower arm switching element,
A constant voltage circuit connected to an output terminal which is a connection point of the upper arm switching element and the lower arm switching element;
A latch circuit for latching the signal at the upper arm switching element and the lower arm switching element timing are both off,
With
The constant voltage circuit outputs an “H” signal when the voltage at the output terminal is substantially equal to the power supply voltage for driving the motor, and outputs an “L” signal when the voltage at the output terminal is substantially zero.
The voltage level of the “H” signal is substantially constant regardless of the motor drive power supply voltage when the motor drive power supply voltage changes within a predetermined range.
The voltage level of the “L” signal is zero.
A current polarity detection circuit. The current polarity detection circuit according to claim 1,
A current polarity detection circuit, wherein the constant voltage circuit includes a MOS transistor or a bipolar transistor . The current polarity detection circuit according to claim 1 ,
The current polarity detection circuit, wherein the constant voltage circuit includes a Zener diode . The semiconductor device characterized by comprising any one of the current polarity detection circuit of claims 1 to 3.

Images