JP2008228371A - Drive controller of electric motor for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive controller of an electric motor for a vehicle that can make the energy withstand capacity of a driver increase and perform high-frequency duty drive, without increasing the number of drivers. <P>SOLUTION: A Zener diode 4 is used to absorb energy generated when a MOS transistor 3a is turned off at the time of normal control. As a result, the energy is consumed by the MOS transistor 3a while an electric motor 2 is driven, and consumed by the Zener diode 4, when the drive of the electric motor 2 is stopped. Furthermore, at the occurrence of load dumping, the magnitude of a voltage caused then can be suppressed to a clamp voltage of the Zener diode 4 by turning on a first switch 5. Thus, excessive energy consumption by the MOS transistor 3a can be prevented, and neither increase in energy withstand capacity of the driver nor increase in the number of drivers is required, so that high-frequency PWM drive becomes compatible with a countermeasure for the load dumping. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive control device for an electric motor for a vehicle that controls driving of an electric motor by controlling on / off of a semiconductor switching element.

2. Description of the Related Art Conventionally, there is a drive control device for a vehicle electric motor that PWM-drives an electric motor by controlling on / off of a semiconductor switching element. When the electric motor is driven by PWM, energy must be absorbed by a surge that occurs when the motor is off. For this reason, conventionally, a plurality of drivers composed of semiconductor switching elements for driving an electric motor are provided and energy is absorbed by the driver, or a series of a freewheeling diode and a transistor connected in parallel to the electric motor. A technique is employed in which energy from a surge is converted into Joule heat in an electric motor, a reflux diode, and a transistor in a circuit (see, for example, Patent Document 1).
JP 2001-522636 A

  However, in the former method, when the off-time energy is large, it is necessary to increase the energy tolerance of the driver used for driving the electric motor or increase the number of drivers. In addition, in the latter method, in addition to the problem that the heat generation of the electric motor increases, the drive control device is applied to a system in which the regenerative voltage is monitored and the electric motor is turned on again when it falls to a predetermined voltage. In this case, since the regenerative voltage cannot be monitored during the recirculation operation, the high-frequency PWM drive is started after the completion of the recirculation, and the start of the PWM drive is delayed by that amount.

  An object of the present invention is to provide a drive control device for an electric motor for a vehicle that can perform high-frequency PWM driving without increasing the energy tolerance of drivers or increasing the number of drivers.

  In order to achieve the above object, according to the first aspect of the present invention, the first switch (5) is connected in parallel to the electric motor (2), and the monitoring circuit (6) is connected to the semiconductor switching element (3a). The on / off of the first switch is controlled based on the applied voltage, the first switch is turned off when the voltage applied to the semiconductor switching element is less than the first threshold, and the first switch when the voltage is greater than or equal to the first threshold. It is characterized by turning on.

  If it does in this way, the energy at the time of turning off a semiconductor switching element at the time of normal control can be absorbed using Zener diode (4). Thereby, when driving the electric motor, energy can be consumed by the semiconductor switching element, and when driving of the electric motor is stopped, energy can be consumed by the Zener diode. In addition, when a load dump occurs, the magnitude of the voltage generated at that time can be suppressed to the clamp voltage of the Zener diode by turning on the first switch. For this reason, it is possible to prevent excessive consumption of energy in the semiconductor switching element, and it is possible to avoid increasing the energy tolerance of the driver circuit and increasing the number of drivers. Further, since the period during which the regenerative voltage cannot be monitored is short compared to the aspect employing the reflux system as shown in Patent Document 1, subsequent high-frequency duty driving can be started early. Thus, it is possible to achieve both high-frequency PWM driving and load dump countermeasures.

  According to the second aspect of the present invention, the temperature detection circuit (11) for detecting the temperature of the semiconductor switching element and the second detection circuit that is on / off controlled by the temperature detection circuit to switch the connection state between the semiconductor switching element and the Zener diode. When the temperature of the semiconductor switching element is lower than the second threshold (K2) in the temperature detection circuit, the Zener diode is disconnected from the semiconductor switching element by the second switch, and the temperature of the semiconductor switching element is When the second threshold value is exceeded, a Zener diode is connected to the semiconductor switching element.

  In this way, it is possible to determine whether the energy for stopping the driving of the electric motor is consumed by the Zener diode or the driver circuit according to the temperature of the semiconductor switching element. Then, until the semiconductor switching element reaches the second threshold value (high temperature), the energy consumed when stopping the driving of the electric motor by the driver circuit is consumed, so that the energy consumption by the Zener diode is reduced. As a result, it is possible to suppress heat concentration on the Zener diode, and to perform higher-speed PWM driving.

  In this case, as described in claim 5, when the temperature of the semiconductor switching element exceeds the second threshold value from a state below the second threshold value, the fourth threshold value (K1) where the temperature of the semiconductor switching element is lower than the second threshold value. If a hysteresis is provided so that a Zener diode is connected to the semiconductor switching element until the voltage drops, it is possible to prevent oscillation that causes the second switch to be switched on and off many times.

  According to the third aspect of the present invention, the second switch (12) for switching the connection state between the semiconductor switching element and the Zener diode is provided, and the semiconductor switching element provided in the driver circuit is PWM-controlled by the driving device (7). In this case, the temperature of the semiconductor switching element is estimated by the drive device based on the control state of the semiconductor switching element, and when the estimated temperature of the semiconductor switching element is less than the second threshold (K2), the second switch The zener diode is separated from the semiconductor switching element, and when the temperature of the semiconductor switching element is equal to or higher than the second threshold value, the zener diode is connected to the semiconductor switching element.

  In this way, it is possible to estimate the temperature of the semiconductor switching element by the driving device that controls the on / off of the semiconductor switching element. Thus, the same effect as in the second aspect can be obtained.

  In this case, when the estimated temperature of the semiconductor switching element is equal to or higher than the third threshold (K3) higher than the second threshold in the driving device (7), the unit per unit time of the semiconductor switching element is provided. It is also possible to make the number of on / off switching times less than when it is less than the third threshold.

  As a result, it is possible to suppress the heat generation itself due to the driving / stopping of the electric motor, and it is possible to suppress the temperature rise of the driver circuit and the Zener diode.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment of the present invention will be described. FIG. 1 is a schematic circuit diagram of a drive control device 1 for an electric motor for a vehicle according to the present embodiment. The electric motor 2 shown in the present embodiment is used to drive a pump that performs suction and discharge of brake fluid in a pipeline formed in, for example, a brake fluid pressure control actuator.

  As shown in FIG. 1, the drive control device 1 for the electric motor 2 includes a driver circuit 3, a Zener diode 4, a switch (first switch) 5, and an IG (ignition) high voltage monitoring circuit 6. It is said that.

  The driver circuit 3 includes a MOS transistor 3a that is a semiconductor switching element, and controls energization to the electric motor 2 from a power source (+ BM) such as a battery. The MOS transistor 3a is driven on and off by a control signal from a driving device 7 constituted by a CPU or the like of the brake ECU. The MOS transistor 3a is connected in series to the electric motor 2, and the energization of the electric motor 2 is controlled by controlling the gate potential of the MOS transistor 3a.

  For example, in the case of the N-type MOS transistor 3a, the Zener diode 4 is connected in parallel between both ends (source-drain), the cathode is the high side (drain) of the MOS transistor 3a, and the anode is the low side of the MOS transistor 3a. (Source) is connected. The clamp voltage of the Zener diode 4 (the Zener breakdown voltage (= first threshold value)) is set smaller than the clamp voltage (breakdown voltage) of the MOS transistor 3a. In this configuration, no voltage exceeding the Zener breakdown voltage is applied.

  Further, the switch 5 is constituted by a semiconductor switching element, for example, and is connected in parallel to the electric motor 2. Then, the IG high voltage monitoring circuit 6 monitors whether or not the voltage applied to the drain of the MOS transistor 3a and the cathode side of the Zener diode 4 with the turning on of an IG switch (not shown) is high. On / off control of the switch 5 is performed based on the result. The switch 5 and the IG high voltage monitoring circuit 6 are configured by a one-chip IC 9 as shown in the figure, but may be configured separately.

  FIG. 2 is a circuit diagram showing a specific configuration example of the drive control device 1 for the vehicular electric motor 2 having such a configuration.

  As shown in this figure, the switch 5 is constituted by Darlington-connected NPN transistors 5a and 5b, and the IG high voltage monitoring circuit 6 is constituted by a circuit in which a resistor 6a, a Zener diode 6b and a resistor 6c are connected in series. By using the potential between the Zener diode 6b and the resistor 6c as the base potential of the NPN transistor 5b, the ON / OFF of the NPN transistors 5a and 5b can be controlled. A capacitor 8 for preventing malfunction due to noise is connected between the base of the NPN transistor 5b and the emitter of the NPN transistor 5a.

  Then, the action | operation of the drive control apparatus 1 of the electric motor 2 of this embodiment is demonstrated. FIG. 3 shows respective timing charts during normal control and load dumping, and will be described with reference to this figure.

(1) Operation during normal control When a normal voltage (for example, battery voltage) is applied to the drain side of the MOS transistor 3a, the IG high voltage monitoring circuit 6 determines that a high voltage is not applied, The switch 5 is turned off. For example, when the drive control device 1 of the electric motor 2 has the circuit configuration shown in FIG. 2, the Zener diode 6b prevents the current from flowing to the resistor 6c side, so the potential of the Zener diode 6b and the resistor 6c. Does not exceed the operating potential of the NPN transistors 5a and 5b, and the switch 5 constituted by the NPN transistors 5a and 5b is turned off. Therefore, normal control is performed with the switch 5 turned off.

  Specifically, when the MOS transistor 3a is turned on based on a control signal from the driving device 7 (time points T1 and T3 in FIG. 3A), the voltage VMT applied to the electric motor 2 is a normal voltage. Thus, the electric motor 2 is driven. At this time, since the voltage exceeding the clamp voltage is not applied to the Zener diode 4, the generated energy is consumed by the MOS transistor 3a. Further, when the MOS transistor 3a is turned off based on a control signal from the driving device 7 (time points T2 and T4 in FIG. 3A), a back electromotive force is instantaneously generated, and thereafter the electric motor 2 A voltage VMT having a value corresponding to the rotation speed due to inertia occurs. Due to this counter electromotive force, the voltage VMT between the MOS transistor 3 a and the electric motor 2 is lowered, and a current flows through the Zener diode 4 beyond the clamp voltage of the Zener diode 4. For this reason, the energy generated at this time is consumed by the Zener diode 4. In this way, energy can be dissipated by the MOS transistor 3a while driving the electric motor 2, and energy can be dissipated by the Zener diode 4 when the driving of the electric motor 2 is stopped. Become.

(2) Operation at Load Dump (Surge Occurrence) When a surge voltage exceeding the normal control time is applied to the drain side of the MOS transistor 3a, it is determined by the IG high voltage monitoring circuit 6 that a high voltage has been applied, Switch 5 is turned on. For example, when the drive control device 1 of the electric motor 2 has the circuit configuration shown in FIG. 2, the voltage of the Zener diode 6b and the resistor 6c exceeds the clamp voltage of the Zener diode 6b and current flows to the resistor 6c side. It exceeds the operating potential of the NPN transistors 5a and 5b. For this reason, the switch 5 including the NPN transistors 5a and 5b is turned on (time T5 in FIG. 3B). At the same time, since a voltage equal to or higher than the clamp voltage is applied to the Zener diode 4, a current flows through the Zener diode 4 (time point T6 in FIG. 3B). For this reason, a load dump current (surge current) can be released.

  As described above, in this embodiment, the Zener diode 4 is used to absorb energy when the MOS transistor 3a is turned off during normal control. Thus, energy can be consumed by the MOS transistor 3a when the electric motor 2 is driven, and energy can be consumed by the Zener diode 4 when driving of the electric motor 2 is stopped. For this reason, it is possible to prevent the MOS transistor 3a from excessively consuming energy, so that it is not necessary to increase the energy tolerance of the driver or increase the number of drivers. In addition, since the period during which the regenerative voltage cannot be monitored can be shortened as compared with the aspect employing the reflux method as shown in Patent Document 1, it is possible to turn on the electric motor 2 again after monitoring the regenerative voltage. Even if it exists, it becomes possible to start high frequency PWM drive at an early stage. As such a Zener diode 4, a conventionally provided Zener diode 4 for releasing a surge current when a surge such as a load dump occurs can also be used.

(Second Embodiment)
A second embodiment of the present invention will be described. The drive control device 1 for the electric motor 2 shown in the first embodiment makes it possible to perform sufficiently high-speed PWM drive. However, even higher-speed PWM drive is desired as a countermeasure against vehicle vibration noise. However, as the PWM drive of the electric motor 2 becomes faster, the energy when the drive of the electric motor 2 is stopped is larger than the energy during the drive, so that the energy consumption in the Zener diode 4 is larger than the energy consumption in the MOS transistor 3a. Since energy consumption increases and heat concentration on the Zener diode 4 occurs, the drive device 7 of the electric motor 2 shown in the first embodiment is limited to high-speed PWM drive (for example, PWM drive with a cycle of about 50 Hz). Heat dispersion possible). Therefore, in the present embodiment, the drive control device 1 for the electric motor 2 of the first embodiment is made to be able to perform PWM driving at higher speed.

  FIG. 4 is a schematic circuit diagram of the drive control device 1 for the electric motor 2 according to the present embodiment. As shown in this figure, in the present embodiment, the temperature detection circuit 11 is incorporated in the driver circuit 3 and the switch (second) in the drive control device 1 for the electric motor 2 shown in the first embodiment. The switch) 12 is different.

  The temperature detection circuit 11 incorporated in the driver circuit 3 detects a temperature rise due to heat generation of the MOS transistor 3a, determines whether or not the temperature of the driver circuit 3 has reached a predetermined threshold value, and the determination result An output signal corresponding to is generated. The switch 12 is driven on and off based on the output signal of the temperature detection circuit 11 and is provided between the anode of the Zener diode 4 and the low side (cathode) of the MOS transistor 3 a in the driver circuit 3. . Therefore, the Zener diode 4 and the electric motor 2 are connected when the switch 12 is turned on, and the Zener diode 4 and the electric motor 2 are not connected when the switch 12 is turned off.

  FIG. 5 is a circuit diagram illustrating a specific configuration example of the drive control device 1 for the electric motor 2 having the above configuration. Since the IG high voltage monitoring circuit 6 is the same as that shown in FIG. 2, it is shown in a block diagram.

  As shown in this figure, the temperature detection circuit 11 controls on / off of the switch 12 based on, for example, the forward voltage V1 of the plurality of diodes 20, and controls the connection state of the Zener diode 4 and the electric motor 2. Of the temperature detection circuit 11, only the diode 20 having temperature characteristics is formed in the driver circuit 3, but another configuration of the temperature detection circuit 11 may be formed in the driver circuit 3.

  Specifically, a voltage is applied from the constant voltage source 25 to the diode 20 via the resistor 27, and the forward voltage V 1 of the diode 20 is input to the inverting input terminal of the comparator 22 via the resistor 21. Thus, it is determined whether or not the temperature of the MOS transistor 3a, which is a semiconductor switching element, exceeds a threshold value by comparing with the reference voltage Vref input to the non-inverting input terminal. The reference voltage Vref input to the non-inverting input terminal is formed, for example, by dividing the voltage of a constant voltage source, which is a 5V power source, by resistors 23 and 24.

  A resistor 26 is provided between the output terminal of the comparator 22 and the constant voltage source 25, and the potential when the output from the comparator 22 becomes high level is fixed at 5V.

  Hysteresis is formed between the threshold value (second threshold value) when the output of the comparator 22 is switched from the low level to the high level and the threshold value (fourth threshold value) when the output is switched from the high level to the low level. .

  The potential of the output terminal of the comparator 22 is input as the gate potential of the MOS transistor 29 via the input protection resistor 28. Thus, the operation of the MOS transistor 29 is controlled, the potential between the resistors 30 and 31 connected in series to the high side (drain) of the MOS transistor 29 is controlled, and both ends of the resistor 31 are used as emitter-base. It controls on / off of the switch 12 composed of a PNP transistor. In this way, the connection state between the Zener diode 4 and the electric motor 2 is controlled.

  The capacitor 32 connected to the inverting input terminal of the comparator 22 is provided for noise removal.

  The drive control apparatus 1 for such an electric motor 2 will be described. However, the drive control device 1 for the electric motor 2 of the present embodiment differs from the first embodiment only in the operation during normal control, and the operation during load dumping is the same as that in the first embodiment, so that normal control is performed. Only the operation will be described.

  During normal control, when the temperature of the driver circuit 3 is relatively low, the switch 12 is turned off by the control signal of the temperature detection circuit 11. For example, when the temperature detection circuit 11 has the circuit configuration of FIG. 5, the forward voltage V1 of the diode 20 is large when the temperature of the driver circuit 3 is relatively low. For this reason, the potential of the inverting input terminal of the comparator 22 becomes larger than the potential of the non-inverting input terminal, and the output of the comparator 22 becomes a low level. As a result, the MOS transistor 29 is turned off, and the switch 12 constituted by the PNP transistor is also turned off.

  Therefore, when the temperature of the driver circuit 3 is relatively low, not only during the driving of the electric motor 2 but also the energy generated when the driving is stopped is consumed by the MOS transistor 3a.

  On the other hand, when the driver circuit 3 becomes high temperature and exceeds the threshold value, the switch 5 is turned on by the control signal of the temperature detection circuit 11. For example, when the temperature detection circuit 11 has the circuit configuration shown in FIG. 5, the forward voltage V1 of the diode 20 decreases as the temperature of the driver circuit 3 increases. For this reason, the potential of the inverting input terminal of the comparator 22 becomes smaller than the potential of the non-inverting input terminal, and the output of the comparator 22 becomes high level. As a result, the MOS transistor 29 is turned on, and the switch 12 composed of the PNP transistor is also turned on.

  Therefore, when the temperature of the driver circuit 3 exceeds the threshold value, energy is consumed by the MOS transistor 3a while the electric motor 2 is being driven, and energy is consumed by the Zener diode 4 when the driving of the electric motor 2 is stopped.

  In the comparator 22, hysteresis is formed in the threshold when the output is switched from the low level to the high level and the threshold when the output is switched from the high level to the low level. Therefore, it is possible to prevent an oscillation state in which the output of the comparator 22 is repeatedly switched and the switch 12 is repeatedly switched on and off many times.

  That is, when the temperature of the driver circuit 3 is relatively low, the forward voltage V1 of the diode 20 is higher than the reference voltage Vref, so that the output of the comparator 22 becomes low level. However, the temperature of the driver circuit 3 rises and the diode 20 When the forward voltage V1 becomes smaller than the reference voltage, the output of the comparator 22 becomes high level. At this time, the comparator 22 having hysteresis is used so that the forward voltage V1 of the diode 20 does not change greatly due to the influence of noise or the like. FIG. 6 is a diagram showing the relationship between the temperature of the driver circuit 3 and the forward voltage V1 of the diode 20, the corresponding change in the output of the comparator 22 and the on / off state of the switch 12.

  As shown in this figure, when the temperature of the driver circuit 3 reaches K2 (second threshold), the output (Vcom) of the comparator 22 is switched from low level to high level, and the switch 12 is also switched from off to on. Once the output of the comparator 22 becomes high level, the output of the comparator 22 is not switched from high level to low level until the temperature of the driver circuit 3 becomes K1 (fourth threshold value) lower than K2, and the switch 12 is also switched. Does not switch from on to off. This prevents the output of the comparator 22 from entering an oscillation state.

  As described above, according to the present embodiment, it is determined whether the energy for stopping the driving of the electric motor 2 is consumed by the Zener diode 4 or the driver circuit 3 according to the temperature of the driver circuit 3. ing. The energy consumed by the Zener diode 4 is reduced by consuming energy when the driving of the electric motor 2 is stopped by the driver circuit 3 until the temperature of the driver circuit 3 becomes high. As a result, heat concentration on the Zener diode 4 can be suppressed, and it is possible to perform even faster PWM drive.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 7 is a schematic circuit diagram of the drive control device 1 for the electric motor 2 according to the present embodiment. As shown in this figure, the present embodiment switches the connection state between the Zener diode 4 and the electric motor 2 by the switch 12 as in the second embodiment. The temperature is not directly detected by the temperature detection circuit 11, but the temperature of the driver circuit 3 is estimated by the drive device 7 that drives the MOS transistor 3a constituting the drive circuit. For example, the heat generation of the MOS transistor 3a can be estimated based on the driving pattern of the MOS transistor 3a, for example, the energization time or the non-energization time. For this reason, the switch 12 is switched on and off based on the estimation result of the temperature of the driver circuit 3 by the driving device 7.

  Then, the action | operation of the drive control apparatus 1 of the electric motor 2 of this embodiment is demonstrated. However, the drive control device 1 for the electric motor 2 according to the present embodiment also differs from the first embodiment only in the operation during normal control, and the operation during load dump is the same as that in the first embodiment. Only the operation will be described.

  FIG. 8 shows a timing chart during normal control. As shown in the period Ta in this figure, the switch 12 is turned off when the temperature of the driver circuit 3 estimated by the driving device 7 is lower than the temperature K2 (second threshold). For this reason, until the temperature of the driver circuit 3 reaches the temperature K2, the energy when the driving of the electric motor 2 is stopped by the driver circuit 3 is consumed so that the energy consumption by the Zener diode 4 is reduced. .

  Subsequently, as in the period Tb in the figure, the switch 12 is turned on while the temperature of the driver circuit 3 estimated by the driving device 7 is between the temperature K2 and the temperature K3 (third threshold value). Thus, when the temperature of the driver circuit 3 is between the temperatures K2 and K3, energy is consumed by the driver circuit 3 while the electric motor 2 is being driven, and energy is consumed by the Zener diode 4 when the driving of the electric motor 2 is stopped. Consume.

  When the temperature of the driver circuit 3 estimated by the drive device 7 further rises and exceeds the temperature K3 as in the period Tc in the figure, the energization pattern of the MOS transistor 3a, that is, the drive pattern of the electric motor 2 is changed. The number of times the electric motor 2 is driven / stopped per unit time is set to be smaller than when the temperature of the driver circuit 3 is lower than the temperature K3. Thereby, it is possible to suppress the heat generation itself due to the driving / stopping of the electric motor 2, and it is possible to suppress the temperature rise of the MOS transistor 3a and the Zener diode 4.

  As described above, the temperature of the driver circuit 3 can be estimated by the drive circuit that controls on / off of the energization of the MOS transistor 3a, and on / off of the switch 12 can be controlled based on the estimation result.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. FIG. 9 is a schematic circuit diagram of the drive control device 1 for the electric motor 2 according to the present embodiment. As shown in this figure, an MT (motor) monitor circuit 40 is provided for the circuit configuration of the first embodiment. Since the MT monitor circuit 40 is provided, the drive device 7 turns on the MOS transistor 3a from the MT monitor circuit 40 even though the drive device 7 turns off the MOS transistor 3a which is a semiconductor switching element. When a signal to the effect is detected, a short circuit of the MOS transistor 3a or a short circuit failure of the Zener diode 4 can be detected.

  In addition to the MT monitor circuit 40, a power supply monitor circuit 41 is also provided. If such a power supply monitor circuit 41 is added, based on the magnitude of the potential difference between both ends of the MOS transistor 3a and the Zener diode 4 (difference between the detection voltage of the power supply monitor circuit 41 and the detection voltage of the MT monitor circuit 40), It is possible to identify the element that caused the short failure. That is, the potential difference between both ends when the MOS transistor 3a is short-circuited (about 0.2V) <the potential difference between both ends when the Zener diode 4 is short-circuited (about 1V). Is possible.

  In this embodiment as well, it is preferable to determine a failure only when an abnormality is detected continuously for a predetermined time in order to prevent erroneous detection due to noise.

(Fifth embodiment)
A fifth embodiment of the present invention will be described. FIG. 10 is a schematic circuit diagram of the drive control device 1 for the electric motor 2 according to the present embodiment. As shown in this figure, a clamp circuit 42 is provided in the driver circuit 3 with respect to the circuit configuration of the first embodiment. In such a configuration, it is possible to detect a disconnection abnormality of the Zener diode 4 by detecting that the driver device 7 is clamping the driver circuit 3 by the clamp circuit 42.

  In this embodiment as well, it is preferable to determine a failure only when an abnormality is detected continuously for a predetermined time in order to prevent erroneous detection due to noise.

(Sixth embodiment)
A sixth embodiment of the present invention will be described. FIG. 11 is a schematic circuit diagram of the drive control device 1 for the electric motor 2 according to the present embodiment. As shown in this figure, in this embodiment, the structure in the drive device 7 is added with respect to 2nd Embodiment. Since the driver circuit 3 is PWM-controlled based on the drive signal of the drive device 7, the drive device 7 can estimate the temperature of the MOS transistor 3a based on the control state of the MOS transistor 3a. For this reason, by comparing the estimation result with the temperature detection result of the MOS transistor 3a in the driving device 7, it is possible to detect the disconnection abnormality of the Zener diode 4 if a difference occurs in the result.

  In this embodiment as well, it is preferable to determine a failure only when an abnormality is detected continuously for a predetermined time in order to prevent erroneous detection due to noise.

(Other embodiments)
In the first to third embodiments, specific examples of each circuit are given. However, these are merely examples, and other circuit configurations that perform the same operation may be applied.

  In the first to third embodiments, the MOS transistor 3a has been described as an example of the semiconductor switching element constituting the driver circuit 3. However, other elements such as an IGBT may be used.

It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 1st Embodiment of this invention. It is the circuit diagram which showed the specific structural example of the drive control apparatus of the electric motor for vehicles shown in FIG. 4 is a timing chart for each of normal control and load dump. It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 1st Embodiment of this invention. FIG. 5 is a circuit diagram illustrating a specific configuration example of the drive control device for the vehicle electric motor illustrated in FIG. 4. It is the figure which showed the relationship between the temperature of a driver circuit, and the forward voltage V1 of a diode, the change of the output of the comparator corresponding to it, and the ON / OFF state of a switch. It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 3rd Embodiment of this invention. It is a timing chart at the time of normal control. It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 4th Embodiment of this invention. It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 5th Embodiment of this invention. It is a circuit schematic diagram of the drive control apparatus of the electric motor for vehicles concerning 6th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Drive control apparatus, 2 ... Electric motor, 3 ... Driver circuit, 3a ... MOS transistor, 4 ... Zener diode, 5 ... Switch, 6 ... High voltage monitoring circuit, 7 ... Drive apparatus, 11 ... Temperature detection circuit, 12 ... Switch, 20 ... Diode, 21 ... Resistance, 22 ... Comparator, 29 ... MOS transistor

Claims (5)

A driver circuit (3) comprising a semiconductor switching element (3a) connected in series to the electric motor (2) and controlling the driving of the electric motor;
A Zener diode (4) connected in parallel to the semiconductor switching element;
A first switch (5) connected in parallel to the electric motor;
The on / off control of the first switch is controlled based on a voltage applied to the semiconductor switching element, the first switch is turned off when the voltage is less than a first threshold, and the first switch is turned off when the voltage is greater than or equal to the first threshold. A drive control device for an electric motor for a vehicle, comprising: a monitoring circuit (6) for turning on the first switch. A temperature detection circuit (11) for detecting the temperature of the semiconductor switching element;
A second switch (12) that is ON / OFF controlled by the temperature detection circuit and that switches a connection state between the semiconductor switching element and the Zener diode;
When the temperature of the semiconductor switching element is lower than a second threshold (K2), the temperature detection circuit disconnects the Zener diode from the semiconductor switching element by the second switch, and the temperature of the semiconductor switching element is the second threshold. 2. The drive control apparatus for an electric motor for a vehicle according to claim 1, wherein the Zener diode is connected to the semiconductor switching element. A second switch (12) for switching a connection state between the semiconductor switching element and the Zener diode;
The semiconductor switching element provided in the driver circuit is PWM-controlled by a driving device (7), and the driving device estimates the temperature of the semiconductor switching element based on the control state of the semiconductor switching element, and based on the estimation When the temperature of the semiconductor switching element is lower than a second threshold (K2), the second switch disconnects the Zener diode from the semiconductor switching element, and when the temperature of the semiconductor switching element is equal to or higher than a second threshold, the semiconductor The drive control device for an electric motor for a vehicle according to claim 1, wherein the Zener diode is connected to a switching element. When the estimated temperature of the semiconductor switching element is equal to or higher than a third threshold (K3) higher than the second threshold, the driving device (7) sets the number of on / off switching times per unit time of the semiconductor switching element. 4. The drive control device for an electric motor for a vehicle according to claim 3, wherein the drive control device is less than when it is less than a third threshold value. When the temperature of the semiconductor switching element exceeds the second threshold value from a state below the second threshold value, the semiconductor switching element is decreased until the temperature of the semiconductor switching element decreases to a fourth threshold value (K1) lower than the second threshold value. The vehicle electric motor drive control apparatus according to any one of claims 2 to 4, wherein the Zener diode is connected to an element.

Images