JP5153605B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device applicable to an exhaust heat recovery pump motor such as a fuel cell system.

  In general, a fuel cell power generation system can take out electricity directly with high efficiency by electrochemically reacting hydrogen as a fuel and oxygen as an oxidant, and does not emit harmful gases with low noise. It is a power generation system with excellent environmental performance. In particular, recently, it has been developed for small household use using a polymer electrolyte membrane as an electrolyte. In this polymer electrolyte fuel cell system, in order to maintain the optimum temperature condition in preparation for the use of electric power at the time of standby such as at night when the electric power is not used, the fuel cell main body is continuously operated with micro power generation, For example, it is required to maintain the temperature of the circulating cooling water at 70 to 75 ° C.

  In order to make the cooling water temperature constant during standby power generation, for example, an exhaust heat recovery pump motor for recovering exhaust heat obtained from the cooling water through a heat exchanger to a hot water storage tank is detected by a temperature sensor. Although a method of on / off control according to the above is conceivable, there is a time lag from temperature detection to exhaust heat recovery, which causes the occurrence of a hunting phenomenon and causes discomfort due to the generation of intermittent sounds.

  On the other hand, as another control method of the exhaust heat recovery pump motor, it is conceivable that the motor is continuously driven to rotate at an extremely low speed even during standby, and the motor on / off control is not performed. However, during the speed control period based on the rotation command signal when using electric power, etc., an accident such as an overload applied to the rotor causes the rotor to slow down, and the drive current emergency cutoff circuit built into the motor drive IC operates. As a result, safety measures have been taken to control the drive current that flows through the stator coil of the motor so that the rotor will stop urgently. Therefore, the extremely low speed steady rotation of the exhaust heat recovery pump motor cannot be realized.

  In view of the above problems, an object of the present invention is to provide a motor that can realize an emergency stop of a rotor by operating a motor drive current cutoff circuit when the rotor speed is reduced, and can also realize extremely low speed steady rotation based on a rotation command signal. It is to provide a control device.

  In order to solve the above-described problem, the motor control device according to the present invention sets the drive current to flow through the stator coil to zero when the voltage of the rotation command signal is equal to or lower than the first voltage value, and the voltage is When the speed control range is from a voltage value of 1 to a second voltage value exceeding this, a rotational drive circuit that increases or decreases the drive current according to the increase or decrease of the voltage, and when the voltage is within the speed control range A charging circuit that charges a constant current to the timer capacitor, a drive current emergency cutoff circuit that acts on the rotary drive circuit to cut off the drive current when the charging voltage of the timer capacitor reaches a threshold value, and is rotated by a stator coil. In a motor control device including a first discharge circuit that discharges a time-measurement capacitor based on a detection signal generated at each rotation period of the rotor, the voltage is controlled from a first voltage value to a speed control. Until the third voltage value of the first voltage value close range is characterized by having a second discharge circuit for discharging the timing capacitor.

  In the present invention, since the first discharge circuit that operates based on the rotation result information of the rotor is provided, the speed of the rotation command signal is between the first voltage value and the third voltage value in the vicinity thereof. The control range is an extremely low speed region, and the drive current cut-off circuit is usually activated by a longer period of the detection signal. However, the second discharge circuit that operates based on the rotation command signal is provided. Since the timekeeping capacitor C is discharged by the two discharge circuits, the drive current emergency cut-off circuit can be disabled, and extremely low speed can be maintained.

  Such a motor is desirably used for a motor for an exhaust heat recovery pump such as a fuel cell system.

  According to the present invention, an extremely low speed steady rotation can be realized based on a rotation command signal while accompanying a drive current emergency cut-off circuit that operates when the rotor speed is reduced.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram showing an embodiment of a motor control apparatus according to the present invention.

  The brushless motor 10 of this example is a motor for an exhaust heat recovery pump in a polymer electrolyte fuel cell system, and includes a rotor 16 having a rotor magnet 14 inserted through a shaft 12 and a star-connected stator coil X that rotationally drives the rotor. , Y, Z.

The motor control device 20 includes a motor driving IC 30, and the motor driving IC 30 includes a rotation driving circuit 33, a charging circuit 34, a driving current emergency cutoff circuit 37, and a first discharging circuit 40. The rotation drive circuit 33 compares the voltage of the rotation command signal S with the sawtooth input F to generate the pulse width modulation signal M, and applies the stator coils X, Y, and Z to the stator coils X, Y, and Z based on the pulse width modulation signal M. And a drive circuit 32 for flowing drive currents I _X , I _Y , and I _Z.

Here, since the sawtooth input F is not sliced when the voltage of the rotation command signal S is 0 to 1 V in this example, the pulse width modulation signal M is zero output, and the drive currents I _X , I _Y , and I _Z are It does not occur and the rotor 16 does not rotate. Since the sawtooth input F is sliced in the speed control range where the voltage of the rotation command signal S is a first voltage value (for example, 1V) to a second voltage value (for example, 5V), the pulse width modulation signal increases as the voltage increases. The pulse width of M becomes longer, the drive currents I _X , I _Y , and I _Z increase, and the speed of the rotor 16 increases. When the voltage of the rotation command signal S is 5 V or more, the pulse width modulation signal M becomes full width conduction, and the drive currents I _X , I _Y , I _Z become maximum.

The charging circuit 34 compares the voltage of the rotation command signal S with the reference voltage V _f1 (1V), and outputs a charge command signal T when the voltage of the rotation command signal S is equal to or higher than the reference voltage V _f1 ; having a constant current source 36 for charging a constant current I _C to clocking capacitor C by the charging command signal T.

Drive current emergency shutdown circuit 37 includes a comparator 38 the charging voltage V _C by comparing the charging voltage V _C of the timing capacitor C with a reference voltage V _f2 is when the above reference voltage V _f2 which outputs a shutoff signal E And a power-down circuit 39 for turning off the energizing power source of the PWM circuit 31 based on the cutoff command signal E.

The first discharge circuit 40 compares the output signal d from the Hall element H with the reference voltage V _f3 and outputs the rotation detection signal D for each rotation period of the rotor 16 when the voltage of the output signal d is equal to or higher than the reference voltage V _f3. a comparator 41 for outputting, a first discharge transistor T _r1 for discharging the turned on capacitor C for counting when the rotation detection signal D is applied to the base.

The motor driving IC 30 has been used as a commercial product from the past, and the following operation is performed. When the voltage of the rotation command signal S is equal to or lower than the first voltage value (1V), the rotor 16 does not rotate, but when the voltage exceeds the first voltage value (1V), the pulse width modulation signal M is generated and driven. Since the currents I _X , I _Y , and I _Z are generated, the rotor 16 is started, and the speed of the rotor 16 increases and decreases according to the increase and decrease of the voltage of the rotation command signal S. Further, when the voltage of the rotation command signal S becomes equal to or higher than the reference voltage V _f1 (1 V), the constant current IC flows into the timer capacitor C and charges.

Here, when the voltage of the rotation command signal S is equal to or higher than the first voltage value (1V) and the rotor 16 is rotating normally, a rotation detection signal D for each relatively short rotation period of the rotor 16 is obtained. , the charge amount of timing capacitor C which is always charged with a constant current I _C is discharged through the first discharge transistor T _r1, charging voltage V _C is the threshold serving reference voltage of the comparator 38b of the timing capacitor C Since V _f2 is not reached, the cutoff command signal E is not generated. However, when an abnormality such as application of overload occurs in the rotor 16 and the speed of the rotor 16 decreases, the level of the output signal d decreases from the Hall element H and the generation cycle becomes longer. charging voltage V _C of the timing capacitor C by the long period of the discharge period by the transistor T _r1 reaches the reference voltage V _f2, and disabling the PWM circuit 31 shutoff signal E is generated, Thus the rotor 16 is stopped .

The motor control device 20 of the present example has a second discharge that operates based on the rotation command signal S separately from the first discharge circuit 40 that operates based on the rotation result information from the Hall element (rotation detection element) H. A circuit 50 is provided. The second discharge circuit 50 compares the voltage of the rotation command signal S with a reference voltage V _f4 (for example, 2V) as a third voltage value, and outputs a discharge command signal W when the voltage is 2V or less. 51, and a second discharge transistor _Tr2 which is turned on when the discharge command signal W is applied to the base and discharges the time measuring capacitor C. For this reason, when the voltage of the rotation command signal S is 1 to 2 V, it becomes an extremely low speed region in the speed control range, and the drive current is urgent in a state where the first discharge circuit 40 does not work due to the long period of the rotation detection signal D. Although the shut-off circuit 37 is in operation, the shut-off command signal E is not output and the drive current is urgent because the timer capacitor C is discharged with the second discharge transistor _Tr2 turned on based on the rotation command signal S. The interruption circuit 37 can be disabled and the extremely low speed state can be maintained. Since it is not the on / off control of the brushless motor 10, the hunting phenomenon does not occur and the generation of intermittent sound can be prevented.

It is a circuit diagram which shows one Example of the control apparatus of the motor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Brushless motor 12 ... Shaft 14 ... Rotor magnet 16 ... Rotor X, Y, Z ... Stator coil 20 ... Motor controller 30 ... Motor drive IC
31 ... PWM circuit 33 ... rotation drive circuit 34 ... charge circuit 35, 38, 41, 51 ... comparator 36 ... constant current source 37 ... driving current emergency cut-off circuit 39 ... first discharge circuit 50 ... second discharge circuit C ... timing capacitor D ... rotation detection signal S ... rotation command signal M ... pulse width modulation signal d ... output signal E ... shutoff signal F ... sawtooth input H ... Hall element I C _... constant current I _X, I _Y, I _Z ... drive current T ... charge command signal T _r1 ... first discharge transistor T _r2 ... second discharge transistor V _C ... charge voltages V _f1 , V _f2 , V _f3 , V _f4 ... reference voltage W ... discharge command signal

Claims (2)

When the voltage of the rotation command signal is equal to or lower than the first voltage value, the driving current flowing through the stator coil is set to zero, and the speed from the first voltage value to the second voltage value exceeding the voltage is set. A rotation drive circuit that increases or decreases the drive current according to the increase or decrease of the voltage when in the control range, a charging circuit that charges a constant current to the time-capacitor when the voltage is within the speed control range, and the timing A drive current emergency cut-off circuit that cuts off the drive current by acting on the rotation drive circuit when the charging voltage of the capacitor for use reaches a threshold value, and a detection signal generated at each rotation cycle of the rotor driven to rotate by the stator coil In the motor control device including the first discharge circuit for discharging the time measuring capacitor based on the first voltage value, the voltage is within the speed control range from the first voltage value. Control device for motor until the third voltage value of the values closer, characterized in that it comprises a second discharge circuit for discharging the timing capacitor. 2. The motor control device according to claim 1, wherein the motor is a motor for an exhaust heat recovery pump in a fuel cell system.

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