JP2008263752A - Drive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive controller with simple structure for detecting the occurrence of overcurrent on a load. <P>SOLUTION: One end of the field winding of a motor 2 coupled to the fuel pump of a vehicle is connected to a vehicle power supply 4 and the other end is connected to a pair of switching elements 7A, 7B. The switching elements 7A, 7B are arranged in parallel each other. When the temperature Tdet of the switching element 7A detected by a temperature detection circuit 15 is lower than a temperature threshold Tc, only the first switching element 7A is turned on to drive the motor 2. When the detected temperature Tdet is the temperature threshold Tc or more, both the first switching element 7A and the second switching element 7B are turned on to drive the motor 2. While the motor 2 is being driven, the switching elements 7A, 7B are turned off to stop the drive of the motor 2 when the detected voltage Vdet between the drain terminal and the source terminal of the switching element 7A by an overcurrent protection circuit 14 is a first voltage threshold Vrefp is more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive control device that controls driving of a load mounted on a vehicle, a general machine, or the like.

There was a load drive circuit that connected to a load and a switching element formed by a power supply and FET (Field Effect Transistor), etc., and turned on and off to supply power to the load to drive or stop ( For example, see Patent Document 1).
By the way, as shown in FIG. 11, in a motor driving circuit 100 in which a power source E and a switching element 102 are connected to an electric motor (hereinafter referred to as a motor) 101 as a load, a rotor (not shown) of the motor 101 that is rotating. If a mechanical external force is applied, an excessive load current is generated in the internal winding. If the state in which the overcurrent is generated in the winding is left for a long time, the rotor of the motor 101 is burned and cannot be rotated. Therefore, in the above-described conventional technology, the generation of the overcurrent is detected and the driving of the load is stopped. I am letting.

  Here, in the said prior art, it replaces by detecting the voltage between the terminals of a switching element, without detecting the electric current which flows into load directly. That is, in the description using the driving circuit 100 shown in FIG. 11, when a control circuit (not shown) detects the voltage Vdrv across the switching element 102 (between the drain and source) and Vdrv becomes equal to or higher than a predetermined value. Assuming that the motor drive current Imot becomes an overcurrent, the switching element 102 is turned off and the motor 101 is stopped.

However, when the switching element 102 is turned on and a predetermined current flows, the internal temperature rises, and the resistance value (on resistance) also changes due to the temperature change. If the internal resistance value of the switching element 102 changes, the inter-terminal voltage Vdrv also fluctuates. Therefore, in consideration of a wide range of temperature changes of the switching element 102, the overcurrent flowing through the motor 101 is detected by detecting the inter-terminal voltage Vdrv. It was not easy to detect. That is, as shown in FIG. 12, the detection voltage Vdrv has a constant threshold value between the terminal voltages of the switching element 102 corresponding to the steady state of the motor 101 and the occurrence of an overcurrent over the temperature range required for the switching element 102. (Vtrh1 or Vthr2) could not be set.
With respect to the temperature change of the switching element described above, in the above prior art, the load current calculation means provided in the microcomputer calculates the current flowing through the load from the switching element temperature and the voltage between its terminals, The voltage fluctuation is compensated.
JP 11-326400 A

  However, as described above, in the conventional technique, the load current calculation means is required in the microcomputer, so that the configuration is complicated. The present invention has been made in view of the above circumstances, and an object thereof is to provide a drive control device having a simple configuration capable of detecting the occurrence of an overcurrent in a load.

  In order to solve the problems of the present invention, according to the invention of claim 1, when the detected temperature of the switching element is lower than the temperature threshold value or lower than the temperature threshold value, one of the switching elements is turned on. If any of the switching elements is turned off and the detected temperature rises above the temperature threshold or exceeds the temperature threshold, in addition to the switching elements that are already turned on, other switching elements that are in the off state By providing temperature compensation means to further turn on the element, even if the resistance value inside the switching element increases due to temperature change, the drive current that flows through the load is divided by the multiple switching elements that are turned on. Voltage fluctuation is reduced, and overcurrent to the load can be detected with a simple configuration.

  According to the invention of claim 2, when the load is driven by turning on the plurality of switching elements, when the detected voltage becomes equal to or higher than the voltage threshold value, When the load is continuously driven with one of the switching elements in the on state turned off, and the detected voltage is equal to or higher than the second voltage threshold value higher than the voltage threshold value, or the second voltage When it is higher than the threshold value, the switching element is turned off to stop driving the load. As a result, the detection voltage does not exceed the second voltage threshold when noise is temporarily applied to the detection voltage, so that it is not erroneously detected that an overcurrent has passed. Noise resistance (robustness) is improved.

  According to the invention of claim 3, the occurrence of overcurrent is more accurately detected in accordance with the change in the resistance value of the switching element due to the temperature change by changing the voltage threshold according to the temperature of the switching element. be able to.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. An electric motor (hereinafter referred to as a motor) 2 of the motor drive control device 1 has a configuration corresponding to the load of the present invention, and is connected to a fuel pump (not shown) of the vehicle. The main circuit unit 5 connected to the motor 2 is connected to an engine control ECU 3 and a vehicle power supply 4 of the vehicle, and drives the motor 2 based on a control signal from the engine control ECU 3 to control the rotation operation of the fuel pump. ing.

  One end of the field winding of the motor 2 is connected to the vehicle power source 4 via the noise preventing smoothing circuit 6 of the main circuit unit 5, and a pair of switching elements (first switching element 7 </ b> A, A second switching element 7B) is connected. The switching elements 7A and 7B are not limited to this, but in this embodiment, an n-channel enhancement mode power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is used. The source terminal is grounded while being connected to the winding of the motor 2, and the switching elements 7A and 7B are arranged in parallel with each other. The first switching element 7 </ b> A and the second switching element 7 </ b> B supply power from the vehicle power source 4 to the motor 2 by being turned on when a predetermined signal is input to the gate terminal.

  The gate terminal of the first switching element 7A is directly connected to the output terminal of the drive circuit 8 (corresponding to the load driving means of the present invention), and the first switching element 7A is connected to the gate terminal from the drive circuit 8. The motor 2 is driven by being turned on based on the drive signal DS1. Note that a free-wheeling diode 9 is connected between the smoothing circuit 6 and the drain terminals of the switching elements 7A and 7B to allow a reverse electromotive force generated in the motor 2 to flow.

  On the other hand, the input signal conversion circuit 10 of the main circuit unit 5 is connected to the engine control ECU 3 and D / A converts a signal instructing the rotation state of the motor 2 from the engine control ECU 3 and increases its frequency. The motor voltage detection circuit 11 is connected to the vehicle power supply 4 and the drain terminals of the switching elements 7A and 7B, and detects the voltage across the motor 2. The signal processing circuit 12 is connected to the input terminal of the drive circuit 8, the input signal conversion circuit 10, the motor voltage detection circuit 11, and the oscillation circuit 13. The signal processing circuit 12 receives the signal from the engine control ECU 3 and the voltage across the motor 2 by the motor voltage detection circuit 11. Based on the comparison, a PWM signal for controlling the rotation operation of the motor 2 is transmitted to the drive circuit 8 based on the comparison.

  The overcurrent protection circuit 14 (corresponding to the overcurrent protection means of the present invention) is for preventing the main circuit unit 5 or the motor 2 from being destroyed due to the overcurrent generated by the locking of the motor 2. The drive circuit 8, the signal processing circuit 12, and the oscillation circuit 13 are connected. The overcurrent protection circuit 14 is also connected to the drain terminals of the switching elements 7A and 7B, detects the voltage Vdet between the drain terminal and the source terminal of the switching elements 7A and 7B, and uses this to detect a predetermined voltage threshold. Compared with the values Vrefp and Vrefs, when the detected voltage Vdet is higher than the first voltage threshold Vrefp or the second voltage threshold Vrefs, the switching elements 7A and 7B are turned off by transmitting to the drive circuit 8 And has a function of stopping the driving of the motor 2.

  Here, the first voltage threshold value Vrefp is set in consideration of variations in detection accuracy between the detection voltage at the time of steady driving of the motor 2 and the detection voltage at the time of occurrence of overcurrent. Specifically, as will be described later, when the temperature of the first switching element 7A is lower than the temperature threshold value Tc, the detection voltage and the excessive voltage at the time of steady driving of the motor 2 in the state where only the first switching element 7A is turned on. The first switching element 7A and the second switching element 7B are both turned on when the first switching element 7A is positioned between the detected voltage at the time of current generation (locking) and the temperature of the first switching element 7A is equal to or higher than the temperature threshold value Tc. In this state, the motor 2 is set to a constant value so as to be positioned between the detection voltage at the time of steady driving and the detection voltage at the time of occurrence of overcurrent (shown in FIG. 5). The first voltage threshold value Vrefp is preferably set between the detection voltage at the time of steady driving of the motor 2 and the detection voltage at the time of occurrence of the overcurrent, more than at the time of occurrence of the overcurrent.

  On the other hand, when the temperature of the first switching element 7A is equal to or higher than the temperature threshold Tc, the second voltage threshold value Vrefs is changed from the state in which both the first switching element 7A and the second switching element 7B are turned on to the second switching threshold value Vrefs. By turning off the element 7B, the voltage is set to be higher than the first voltage threshold Vrefp by an amount corresponding to the amount of increase in the voltage between the drain terminal and the source terminal of the first switching element 7A.

  The temperature detection circuit 15 (corresponding to the temperature compensation means of the present invention) is connected to the overcurrent protection circuit 14 and to an input terminal on one side of the AND circuit 16. The other input terminal of the AND circuit 16 is connected to the output terminal of the drive circuit 8, and the output terminal of the AND circuit 16 is connected to the gate terminal of the second switching element 7B. The temperature detection circuit 15 includes, for example, a thermistor that detects the temperature of the first switching element 7A, and the detected temperature of the first switching element 7A is a preset temperature threshold value Tc (limited to this). However, for example, when the temperature is lower than 55 degrees Celsius (−30 degrees Celsius to less than 55 degrees Celsius), there is no transmission to the input terminal of the AND circuit 16, and the detected temperature of the first switching element 7A is increased. When it is equal to or higher than the threshold value Tc (55 ° C. or higher and 150 ° C. or lower), transmission to the input terminal of the AND circuit 16 is performed.

  Next, a method for driving the motor 2 by the motor drive control device 1 according to the present embodiment will be described with reference to FIG. When the user activates the key switch of the vehicle, power is supplied from the vehicle power source 4 to the main circuit unit 5 and the engine control ECU 3 requests activation of the fuel pump (step S601 in FIG. 6). Next, in step S602, the temperature detection circuit 15 of the main circuit unit 5 detects the temperature Tdet of the first switching element 7A and compares it with the temperature threshold value Tc (step S603). When the detected temperature Tdet of the first switching element 7A is lower than the temperature threshold value Tc (55 ° C.), the drive signal DS1 is sent from the drive circuit 8 to the gate terminal of the first switching element 7A and the input terminal of the AND circuit 16. Although it is transmitted, there is no transmission from the temperature detection circuit 15 to the input terminal of the AND circuit 16, and therefore there is no transmission of the drive signal DS2 from the AND circuit 16 to the second switching element 7B. Accordingly, when only the first switching element 7A is turned on (single drive) in a state where the second switching element 7B is turned off, electric power is supplied from the vehicle power supply 4 to the motor 2 to drive the motor 2. (Step S604).

  Next, in step S605, the overcurrent protection circuit 14 detects the voltage Vdet between the drain terminal and the source terminal of the first switching element 7A, and compares the detected voltage Vdet with the first voltage threshold value Vrefp (step S606). When the detection voltage Vdet is equal to or higher than the first voltage threshold value Vrefp, a timer in the overcurrent protection circuit 14 is started on the assumption that overcurrent starts to flow through the motor 2 due to pump lock or the like (step S607). If it is determined in step S608 that the predetermined time tm has elapsed after the timer is started, the drive signal DS1 from the drive circuit 8 is not transmitted by the transmission from the overcurrent protection circuit 14 to the drive circuit 8, and the second switching element In addition to 7B, the first switching element 7A is also turned off, and the drive of the motor 2 is stopped (step S609). Thereafter, predetermined motor overcurrent measures such as notifying the vehicle user that the fuel pump has been stopped are performed (step S610). If it is determined in step S606 that the detected voltage Vdet is less than the first voltage threshold value Vrefp, the driving of the motor 2 is continued with only the first switching element 7A turned on.

  Next, in step S611, it is determined whether or not to stop the operation of the fuel pump. When it is determined that the user stops the pump, for example, by stopping the engine of the vehicle, the drive signal DS1 is not transmitted from the drive circuit 8, and the first switching element 7A is turned off in addition to the second switching element 7B. 2 is stopped (step S612). When continuing the operation of the fuel pump, the process returns from step S611 to step S602, and the above-described processing is repeated.

  On the other hand, when the temperature Tdet of the first switching element 7A detected by the temperature detection circuit 15 becomes equal to or higher than the temperature threshold value Tc (55 degrees Celsius) in step S603, the drive circuit 8 to the gate of the first switching element 7A. The drive signal DS1 is transmitted to the terminal and the input terminal of the AND circuit 16, and is transmitted from the temperature detection circuit 15 to the input terminal of the AND circuit 16, and the drive signal DS2 is transmitted from the AND circuit 16 to the second switching element 7B. The Thereby, the second switching element 7B is turned on in addition to the first switching element 7A (parallel drive: step S621). At this time, since the current flowing from the vehicle power supply 4 to the motor 2 is shunted by the switching elements 7A and 7B arranged in parallel with each other, the switching element is controlled regardless of the increase in internal resistance accompanying the temperature rise of the switching elements 7A and 7B. The voltage between the drain terminal and the source terminal of 7A and 7B is reduced.

  Thereafter, in step S622, the overcurrent protection circuit 14 detects the voltage Vdet between the drain terminal and the source terminal of the first switching element 7A, and compares the detected voltage Vdet with the first voltage threshold value Vrefp as in the case described above. (Step S623). When the detection voltage Vdet is equal to or higher than the first voltage threshold value Vrefp, a timer in the overcurrent protection circuit 14 is started (step S624). If it is determined in step S625 that the predetermined time tm has elapsed after the timer is started, the temperature detection circuit 15 stops transmitting to the input terminal of the AND circuit 16 based on the transmission from the overcurrent protection circuit 14, and the drive signal DS2 And the drive of the motor 2 is continued with the second switching element 7B turned off (step S626). In a state where only the first switching element 7A is turned on, it is determined whether or not the detection voltage Vdet detected by the overcurrent protection circuit 14 is equal to or higher than the second voltage threshold value Vrefs (step S627). If the detected voltage Vdet is equal to or higher than the second voltage threshold value Vrefs, it is determined that an overcurrent has occurred in the motor 2, and the process proceeds to step S607, where the operation of the motor 2 is stopped as described above.

  When the detection voltage Vdet is less than the second voltage threshold value Vrefs, the detection voltage Vdet becomes equal to or higher than the first voltage threshold value Vrefp in step S623 as described above. Therefore, the timer in the overcurrent protection circuit 14 is started (step S628). In step S629, when it is determined that the predetermined time tm has elapsed after the timer is started, transmission from the overcurrent protection circuit 14 to the temperature detection circuit 15 causes transmission from the temperature detection circuit 15 to the input terminal of the AND circuit 16. Again, the drive signal DS2 is transmitted from the AND circuit 16 to the second switching element 7B. Accordingly, the second switching element 7B is turned on again in addition to the first switching element 7A (step S630). Thereafter, the process proceeds to step S611, and the same process as described above is performed. If it is determined in step S623 that the detected voltage Vdet is less than the first voltage threshold value Vrefp, the process proceeds to step S611 and the same process is performed.

  Next, based on FIGS. 2 to 4, the generation of each signal and the characteristic change of the motor drive control device 1 in this embodiment will be described. As shown in FIG. 2, when the temperature Tdet of the first switching element 7A detected by the temperature detection circuit 15 is lower than the temperature threshold value Tc, a drive signal DS1 is transmitted from the drive circuit 8, and the first switching element 7A. Only is turned on and the motor 2 is driven (step S604 in FIG. 6).

  In this state, when the motor 2 is locked and an overcurrent starts to flow in the winding, and the drain-source current (in other words, the winding current of the motor 2) Irel of the first switching element 7A becomes Iexe or higher, Accordingly, the overcurrent protection circuit 14 detects that the voltage Vdet between the drain terminal and the source terminal of the first switching element 7A is equal to or higher than the first voltage threshold value Vrefp. As a result, the drive signal DS1 from the drive circuit 8 is turned off after a predetermined time tm by the action of the timer, the first switching element 7A is also turned off in addition to the second switching element 7B, and the driving of the motor 2 is stopped. (Step S609 in FIG. 6).

  As shown in FIG. 3, in the state where only the first switching element 7A is turned on and the motor 2 is driven, the temperature Tdet of the first switching element 7A detected by the temperature detection circuit 15 is equal to or higher than the temperature threshold value Tc. In this case, the drive signal DS2 is transmitted from the AND circuit 16, and the second switching element 7B is turned on in addition to the first switching element 7A (step S621 in FIG. 6).

  In this state, the motor 2 is locked or the like, and the overcurrent protection circuit 14 detects that the voltage Vdet between the drain terminal and the source terminal of the first switching element 7A is equal to or higher than the first voltage threshold value Vrefp. Then, after a predetermined time tm, the drive signal DS2 from the AND circuit 16 is turned off, the second switching element 7B is turned off, and the driving of the motor 2 is continued with only the first switching element 7A turned on. (Step S626 in FIG. 6). When an overcurrent occurs, the overcurrent itself flowing through the first switching element 7A increases when the second switching element 7B is turned off. Therefore, in this state, when the overcurrent protection circuit 14 further detects that the voltage Vdet between the drain terminal and the source terminal of the first switching element 7A is equal to or higher than the second voltage threshold value Vrefs, The drive signal DS1 from the drive circuit 8 is turned off a predetermined time tm after the switching element 7B is turned off, and the first switching element 7A is turned off in addition to the second switching element 7B, thereby driving the motor 2. Is stopped (step S609 in FIG. 6).

  As shown in FIG. 4, when a noise signal equal to or higher than the first voltage threshold value Vrefp is on the detection voltage Vdet from the state where the first switching element 7A and the second switching element 7B are turned on, after a predetermined time tm, In a state where the signal DS2 from the AND circuit 16 is turned off, only the first switching element 7A is turned on, and the driving of the motor 2 is continued, the overcurrent protection circuit 14 is connected to the drain terminal of the first switching element 7A. When it is detected that the voltage Vdet between the source terminals is lower than the second voltage threshold value Vrefs, the drive signal DS2 is transmitted from the AND circuit 16 again after a predetermined time tm after the second switching element 7B is turned off. Thus, the driving of the motor 2 is continued with the second switching element 7B being turned on in addition to the first switching element 7A ( 6 step S630).

  As described so far, according to the present embodiment, when the temperature Tdet of the first switching element 7A detected by the temperature detection circuit 15 is lower than the temperature threshold value Tc, the drive circuit 8 causes the first switching element 7A. When the temperature Tdet of the first switching element 7A becomes equal to or higher than the temperature threshold value Tc, the second switching element 7B is turned on in addition to the first switching element 7A. Is driven. As a result, even if the resistance value inside the first switching element 7A increases due to temperature change, the winding current flowing through the motor 2 is shunted by the pair of switching elements 7A and 7B that are turned on, so that the detection voltage Vdet Variations can be reduced. Therefore, the voltage threshold value Vrefp can be set over the detected temperature range (shown in FIG. 5), and an overcurrent to the motor 2 can be detected with a simple configuration.

  Further, when the motor 2 is driven while the pair of switching elements 7A and 7B are turned on, the second switching element that is in the on state when the detected voltage Vdet is equal to or higher than the first voltage threshold value Vrefp. When the motor 2 is continuously driven with 7B turned off, and the detected voltage Vdet is equal to or higher than the second voltage threshold Vrefs higher than the first voltage threshold Vrefp, the first switching element 7A is The drive of the motor 2 is stopped by turning it off. With this configuration, when noise temporarily occurs in the detection voltage Vdet, the detection voltage Vdet does not exceed the second voltage threshold value Vrefs even if the second switching element 7B is turned off. It is not erroneously detected that an overcurrent has flowed, and the noise resistance (robustness) of the motor drive control device 1 is improved regardless of the increase in the influence of noise signals due to the recent reduction in resistance of switching elements such as FETs.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described based on FIGS. In the main circuit unit 5A of the motor drive control apparatus 1A according to the present embodiment, three switching elements (first switching element 7A, second switching element 7B, and third switching element 7C) are provided in the field winding of the motor 2. It is connected. Also in this embodiment, the drain terminals of the switching elements 7A, 7B, and 7C are connected to the winding of the motor 2 and the source terminal is grounded, and the switching elements 7A, 7B, and 7C are arranged in parallel to each other. . The gate terminal of the first switching element 7 </ b> A is directly connected to the output terminal of the drive circuit 8.

  On the other hand, the temperature detection circuit 15 is connected to one input terminal of each of the pair of AND circuits 16A and 16B. The other input terminals of the AND circuits 16A and 16B are connected to the drive circuit 8, the output terminal of the AND circuit 16A is connected to the gate terminal of the second switching element 7B, and the output terminal of the AND circuit 16B is the third switching terminal. It is connected to the gate terminal of the element 7C (shown in FIG. 7).

  With this configuration, according to the present embodiment, when the temperature Tdet of the first switching element 7A detected by the temperature detection circuit 15 is lower than the first temperature threshold value Tc1, only the first switching element 7A is driven by the drive circuit 8. Is turned on and the motor 2 is driven, and the temperature Tdet of the first switching element 7A is equal to or higher than the first temperature threshold Tc and lower than the second temperature threshold Tc2, in addition to the first switching element 7A. When the second switching element 7B is turned on to drive the motor 2, and when the temperature Tdet of the first switching element 7A becomes equal to or higher than the second temperature threshold value Tc2, the first switching element 7A and the second switching element In addition to 7B, the third switching element 7C is turned on and the motor 2 is driven. As a result, even if the resistance value inside the switching elements 7A and 7B increases due to a temperature change, the variation in the detection voltage Vdet can be finely reduced, and the voltage threshold value Vrefp can be set over a wider detection temperature range (shown in FIG. 8). .

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described based on FIG. 9 and FIG. In the present embodiment, the configuration other than the internal configuration of the overcurrent protection circuit 14 is the same as the configuration of the first embodiment described above. In FIG. 9, the overcurrent protection circuit 14 includes a temperature detection diode SD connected to the vehicle power supply 4. A plurality of temperature detection diodes SD are connected in series, the anode side thereof is connected to the vehicle power supply 4, and the cathode side is connected to a pair of DC resistors R1 and R2. Between the DC resistors R1 and R2, the + side input terminal of the comparator CP is connected to input the first voltage threshold value Vrefp, and the drain terminals of the switching elements 7A and 7B are connected to the − side input terminal of the comparator CP. The detection voltage Vdet between the drain terminal and the source terminal is input. The output terminal of the comparator CP is connected to the input terminal of the drive circuit 8 via the timer TM.

The temperature detection diode SD is for changing the first voltage threshold value Vrefp in accordance with the temperature change of the first switching element 7A, and is on the same chip as the first switching element 7A or other than the main circuit unit 5. Provided on the chip of the electronic element. When the temperature detection diode SD is provided on a chip of an element other than the first switching element 7A of the main circuit unit 5, the temperature of the first switching element 7A is detected by detecting the temperature of other elements on the chip. It will be substituted for detection. The first voltage threshold value Vrefp input to the comparator CP changes in the voltage value between the DC resistances R1 and R2 due to the change in the resistance value due to the temperature change of the temperature detection diode SD. It fluctuates according to the temperature change of the element 7A (if the temperature of the first switching element 7A increases, the first voltage threshold value Vrefp also increases).
According to the present embodiment, the first voltage threshold value Vrefp changes according to the temperature of the first switching element 7A, so that the resistance value of the switching elements 7A and 7B due to the temperature change can be more accurately matched. The occurrence of overcurrent can be detected (shown in FIG. 10).

<Other embodiments>
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.
As the switching element, not only a power MOSFET but also a semiconductor switching element such as a power transistor can be used. Further, the load connected to the switching element is not limited to the motor, and may be a lamp, a buzzer, or the like.

As long as the overcurrent protection circuit includes the voltage between the terminals of the switching element as a part thereof, the overcurrent protection circuit may detect any voltage in the main circuit portion.
Each threshold value Tc, Tc1, Tc2, Vrefp, Vrefs itself of temperature or voltage may be included in any determination region.

The block diagram which shows the motor drive control apparatus by Embodiment 1 of this invention. Time chart showing the operation when the temperature of the switching element of the motor drive control device shown in FIG. 1 is lower than the temperature threshold Time chart showing the operation when the temperature of the switching element of the motor drive controller is above the temperature threshold Time chart showing the operation when noise is added to the detection voltage of the motor drive control device The graph which showed the relationship between the temperature of the switching element of the motor drive control apparatus shown in FIG. 1, and detection voltage The flowchart which showed the control method of the motor drive control apparatus shown in FIG. The block diagram which shows the motor drive control apparatus by Embodiment 2 of this invention. The graph which showed the relationship between the temperature of the switching element of the motor drive control apparatus shown in FIG. 7, and detected voltage Detailed view of essential parts of motor drive control apparatus according to Embodiment 3 of the present invention The graph which showed the relationship between the temperature of the switching element of the motor drive control apparatus shown in FIG. 9, and detected voltage Circuit diagram showing a motor driving device according to the prior art The graph which showed the relationship between the temperature of the switching element of the motor drive unit shown in FIG. 11, and detected voltage

Explanation of symbols

  In the drawings, 1 is a motor drive control device (drive control device), 2 is a motor (load), 7A is a first switching element, 7B is a second switching element, 7C is a third switching element, and 8 is a drive circuit (load drive). Means), 14 is an overcurrent protection circuit (overcurrent protection means), 15 is a temperature detection circuit (temperature compensation means), Tdet is a detected temperature of the switching element, Tc is a temperature threshold value, and Tc1 is a first temperature threshold value. , Tc2 is a second temperature threshold value, Vdet is a voltage between the drain terminal and the source terminal of the switching element, Vrefp is a first voltage threshold value, and Vrefs is a second voltage threshold value.

Claims (3)

A plurality of switching elements each connected to a load and arranged in parallel with each other, each of which is turned on to supply power to the load;
Load driving means for driving one of the switching elements to drive the load;
A voltage that is connected to the load driving means and includes at least a voltage between terminals of the switching element is detected, and the switching element is detected when the detected voltage is equal to or higher than a voltage threshold value or higher than the voltage threshold value. Overcurrent protection means for turning off the load to stop driving the load;
The temperature of the switching element is detected while being connected to the load driving means, and when the detected temperature is lower than the temperature threshold value or lower than the temperature threshold value, one of the switching elements is turned on. When any of the switching elements is turned off and the detected temperature becomes higher than the temperature threshold value or exceeds the temperature threshold value, in addition to the switching element that is already turned on, A drive control apparatus comprising temperature compensation means for further turning on the switching element.   When the overcurrent protection means drives the load by turning on the plurality of switching elements, the detected voltage becomes higher than the voltage threshold or higher than the voltage threshold In this case, the load is continuously driven in a state in which any one of the switching elements in the on state is turned off, and the detected voltage is equal to or higher than a second voltage threshold value that is higher than the voltage threshold value. 2. The drive control device according to claim 1, wherein the switching element is turned off to stop the driving of the load when the voltage is higher than the second voltage threshold value.   The drive control apparatus according to claim 1, wherein the voltage threshold value by the overcurrent protection unit changes according to a temperature of the switching element.

Images