JP2020150764A - Motor system - Google Patents

Abstract

To reduce loss generated in a motor system regardless of a load and an operation condition.SOLUTION: A motor system that converts a DC power from a power supply device to an AC power by a power conversion device and supplies the power to a motor to drive the motor, comprises a control unit that controls an ON state and an OFF state of a switching element structuring the power conversion device. The control unit controls an on fixed conductive period while changing the on fixed conductive period as a period where the switching element is in the ON state so that a total loss containing a loss generated in the motor and a loss generated in the power conversion device becomes the minimum.SELECTED DRAWING: Figure 1

Description

The present invention relates to a motor system.

A motor system that includes an inverter and a motor and drives the motor by converting DC power from a DC power source such as a battery into AC power by the inverter and supplying the motor to the motor is known (for example, Patent Document 1).

International Publication No. 2017/145640

By the way, when the load of the motor is constant, the loss in the motor and the loss in the inverter for driving the motor are also constant, so that the loss generated in the entire motor system is also constant.

However, when the load of the motor fluctuates, the loss in the motor and the loss in the inverter also fluctuate, so that the loss generated in the entire motor system also fluctuates. Therefore, the loss generated in the entire motor system may increase due to the load fluctuation of the motor.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the loss generated in the motor system regardless of the motor load and operating conditions.

(1) One aspect of the present invention is a motor system that drives the motor by converting DC power from a power supply device into AC power by a power conversion device and supplying the motor to the motor, and constitutes the power conversion device. A control unit for controlling the on state and the off state of the switching element is provided, and the control unit changes the on-fixed energization period, which is the period during which the switching element is on, while causing the loss and the electric power of the motor. The motor system includes a control unit that controls the on-fixed energization period so that the total loss including the loss generated in the conversion device is minimized.

(2) In the motor system of (1) above, the control unit may control the on-fixed energization period so that the DC power is minimized.

(3) In the motor system according to the above (1) or (2), the control unit controls the minimum loss point tracking and turns the switching element on and off at a predetermined cycle with respect to the switching element. The control may be executed, and the on-fixed energization period longer than the predetermined period may be provided in the minimum loss point tracking control.

(4) The motor system according to any one of (1) to (3) above, further including a first temperature sensor for measuring the temperature of the switching element, and the control unit using the first temperature sensor. When the measured temperature becomes equal to or higher than the first threshold value, the on-fixed energization period may be forcibly increased.

(5) The motor system according to any one of (1) to (3) above, further including a second temperature sensor for measuring the temperature of the motor, and the control unit measures with the second temperature sensor. When the temperature is equal to or higher than the second threshold value, the on-fixed energization period is forcibly reduced.

As described above, according to the present invention, it is possible to reduce the loss generated in the motor system regardless of the load and operating conditions.

It is a figure which shows an example of the schematic structure of the motor system A provided with the motor drive device which concerns on 1st Embodiment. It is a figure which shows the switching control which concerns on 1st Embodiment. Motor loss P _M according to the first _embodiment, and shows the inverter loss P _IV, and an example of a trend for the switching frequency fs of the total losses P _S. It is a figure explaining the response angular frequency ω _θ which concerns on 1st Embodiment. It is a flow chart of the minimum loss point follow-up control which concerns on 1st Embodiment. It is a flow figure which shows the modification of the minimum loss point follow-up control which concerns on 1st Embodiment. It is a figure which shows an example of the schematic structure of the motor system A provided with the motor drive device which concerns on 1st Embodiment. It is a figure which shows an example of the schematic structure of the motor system B provided with the motor drive device which concerns on 2nd Embodiment. It is a flow chart of the minimum loss point follow-up control which concerns on 2nd Embodiment. It is a flow chart which shows the modification of the minimum loss point follow-up control which concerns on 2nd Embodiment. It is a figure which shows the modification 6 of the control part of the 1st Embodiment and 2nd Embodiment.

Hereinafter, the motor system according to this embodiment will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a diagram showing an example of a schematic configuration of the motor system A according to the first embodiment. As shown in FIG. 1, the motor system A includes a power supply device 1, a motor 2, and a motor drive device 3.

The power supply device 1 is a DC power supply, and for example, a secondary battery such as a nickel hydrogen battery or a lithium ion battery can be used. Further, the power supply device 1 may use an electric double layer capacitor (capacitor) instead of the secondary battery. Further, the power supply device 1 may be a device that rectifies the output from the AC power supply to direct current.

The motor 2 is an electric motor whose drive is controlled by the motor drive device 3. In this embodiment, the motor 2 is a three-phase (U, V, W) brushless motor. Specifically, in the motor 2, a rotor having a permanent magnet and coils Lu, Lv, and Lw corresponding to each of the three phases (U phase, V phase, and W phase) are wound in order in the rotation direction of the rotor. It is equipped with a stator. Each of the coils Lu, Lv, and Lw of each phase is connected to the motor drive device 3.

The motor drive device 3 drives the motor 2 by converting the DC power from the power supply device 1 into AC power and supplying it to the motor 2. The configuration of the motor drive device 3 according to the first embodiment will be specifically described below.

The motor drive device 3 includes an inverter 4 and an inverter control unit 5. The inverter 4 is an example of the "power conversion device" of the present invention.

The inverter 4 converts the DC power from the power supply device 1 into AC power. Then, the inverter 4 supplies the converted AC power to the motor 2.

Specifically, the inverter 4 includes an input terminal N1, a reference terminal N2, and output terminals N3 to N5.

The input terminal N1 is connected to the positive electrode terminal of the power supply device 1 via the connection line L1. The reference terminal N2 is connected to the negative electrode terminal of the power supply device 1 via the connection line L2. Further, a coil Lu is connected to the output terminal N3. A coil Lv is connected to the output terminal N4. A coil Lw is connected to the output terminal N5.
Therefore, the inverter 4 converts the DC power input from the power supply device 1 to the input terminal N1 into AC power and outputs the DC power to the output terminals N3 to N5.

The configuration of the inverter 4 will be specifically described below.

The inverter 4 has a plurality of switching elements SW, and the ON state and the OFF state of the switching elements are switched and controlled by the inverter control unit 5, so that the DC power from the power supply device 1 is converted into AC power and the motor. Output to 2. As a result, the motor 2 is driven. In the present embodiment, the inverter 4 includes three sets of switching elements vs. Su, Sv, and Sw. The switching element pairs Su, Sv, and Sw are connected in parallel between the positive and negative power supply lines from the power supply device 1. The three sets of switching elements vs. Su, Sv, and Sw are turned on and off by the inverter control unit 5 with an electric angle of the motor 2 deviated by 120 degrees.

The switching element pair Su includes a switching element SW1 and a switching element SW2 connected in series with each other. The switching element pair Sv includes a switching element SW3 and a switching element SW4 connected in series with each other. The switching element pair Sw includes a switching element SW5 and a switching element SW6 connected in series with each other.

The case where the six switching elements SW1 to SW6 are FETs (Field Effective Transistors) will be described, but the present invention is not limited to this, and may be, for example, an IGBT (Insulated gate bipolar transistor) and a BJT (bipolar junction transistor). .. Further, the inverter 4 is not particularly limited in the number of switching elements SW. When each of the plurality of switching elements SW1 to SW6 is not distinguished, it is simply labeled as "switching element SW".

Specifically, the switching elements SW1 and SW2 connected in series, the switching elements SW3 and SW4 connected in series, and the switching elements SW5 and SW6 connected in series are the input terminal N1 and the reference terminal N2. It is connected in parallel with.

The drain terminal of the switching element SW1 is connected to the input terminal N1. The source terminal of the switching element SW2 is connected to the reference terminal N2. The connection point (output terminal N3) between the source terminal of the switching element SW1 and the drain terminal of the switching element SW2 is connected to one end of the U-phase coil Lu.

The drain terminal of the switching element SW3 is connected to the drain terminal of the switching element SW1. The source terminal of the switching element SW4 is connected to the reference terminal N2. The connection point (output terminal N4) between the source terminal of the switching element SW3 and the drain terminal of the switching element SW4 is connected to one end of the V-phase coil Lv.

The drain terminal of the switching element SW5 is connected to the drain terminal of the switching element SW1. The source terminal of the switching element SW6 is connected to the reference terminal N2. The connection point (output terminal N5) between the source terminal of the switching element SW5 and the drain terminal of the switching element SW6 is connected to one end of the W-phase coil Lw.

Further, the gate terminals of the switching elements SW1 to SW6 are connected to the inverter control unit 5.
In each switching element pair Su, Sv, Sw, the switching element SW provided on the high potential side is referred to as "high side switching element SW _H ", and the switching element SW provided on the low potential side is referred to as "low side". It may be referred to as "switching element SW _L ". That is, the switching elements SW1, SW3, SW5 is high-side switching element SW _H, the switching elements SW2, SW4, SW6 are low-side switching element SW _L.

The inverter control unit 5 controls the drive of the inverter 4. Specifically, the inverter control unit 5 switches and controls the switching elements SW1 to SW6. The configuration of the inverter control unit 5 will be specifically described below.

The inverter control unit 5 includes a current detection unit 6, a voltage detection unit 7, and a control unit 8.

The current detection unit 6 detects the input current Iin input from the power supply device 1 to the input terminal N1 of the inverter 4. For example, the current detection unit 6 is provided on the connection line L1 and detects the input current Iin by detecting the current flowing through the connection sensor L1. Then, the current detection unit 6 outputs the detected input current Iin to the control unit 8.

The current detection unit 6 is not particularly limited as long as it has a configuration for detecting the input current Iin, but is, for example, a current transformer (CT) including a transformer or a current sensor including a Hall element. Further, the current detection unit 6 may detect the input current Iin from the voltage across the shunt resistor connected in series with the connection line L1.

The voltage detection unit 7 detects the input voltage Vin input to the inverter 4. For example, the voltage detection unit 7 detects the input voltage Vin by detecting the potential difference between the input terminal N1 and the reference terminal N2. The voltage detection unit 7 does not read the input voltage Vin input to the inverter 4 as it is, but for example, the voltage obtained by dividing the input voltage Vin by the resistance voltage divider circuit (hereinafter referred to as “voltage divider voltage”). May be read. In this case, the voltage detection unit 7 calculates the input voltage Vin from the read voltage dividing voltage based on the voltage dividing ratio of the resistance voltage dividing circuit.

The voltage detection unit 7 outputs the detected input voltage Vin to the control unit 8. As described above, since the input terminal N1 is connected to the positive electrode terminal of the power supply device 1 and the reference terminal N2 is connected to the negative electrode terminal of the power supply device 1, the input voltage Vin corresponds to the output voltage of the power supply device 1.

The control unit 8 controls the ON state and the OFF state of the switching elements SW1 to SW6 to convert the DC power from the power supply device 1 into AC power in the inverter 4. For example, the control unit 8 turns on and off the switching elements SW1 to SW6 so that the phases of the currents flowing through the U-phase coil Lu, the V-phase coil Lv, and the W-phase coil Lw are shifted by 120 degrees. Performs switching control to control the state.
At that time, the control unit 8 inputs the DC power input from the power supply device 1 to the inverter 4 while changing the on-fixed energization period θon, which is the period for maintaining the switching element SW in the ON state, in each of the switching elements SW1 to SW6. (Hereinafter, referred to as “input power”.) The minimum loss point tracking control that controls the on-fixed energization period θon so that the Pin is minimized is executed. Therefore, in the present embodiment, the on-fixed energization period θon is not a fixed value but a variable value that fluctuates according to the input power Pin. The on-fixed energization period θon may be a phase width that keeps the switching element SW in the on state.

Hereinafter, an example of switching control of the control unit 8 according to the first embodiment will be described with reference to FIG.
The control unit 8 performs switching control for controlling the switching elements SW1 to SW6 in an on state or an off state by outputting a control signal to the gate terminals of the switching elements SW1 to SW6. For example, the control signal output to the high-side switching element SW _H is referred to as “control signal P”, and the control signal output to the low-side switching element SW _L is referred to as “control signal N”.

The control unit 8 alternately controls the high-side switching element SW _H and the low-side switching element SW _L by switching every half cycle ΔT in one switching pair SW. The control unit 8 multiplies the input current Iin detected by the current detection unit 6 and the input voltage Vin detected by the voltage detection unit 7 during the switching control to obtain the current input power Pin (= Iin × Vin). Is calculated, and the minimum power point tracking control that adjusts the on-fixed energization period θon so that the calculated current input power Pin is minimized is executed. Therefore, each of the control signal P and the control signal N includes an on-fixed energization period θon which is a variable value.

Here, the control unit 8 may PWM control the switching element SW by outputting a PWM signal having a predetermined cycle (PWM cycle) T to each switching element SW. That is, the switching control according to the present embodiment may include at least the minimum power point tracking control, and may further include the PWM control. However, when the switching control includes the minimum loss point tracking control and the PWM control, the control unit 8 provides an on-fixed energization period θon longer than the PWM cycle T of the PWM control in the minimum loss point tracking control. That is, when the control unit 8 performs the switching control and the PWM control is included in the switching control, the control unit 8 sets the PWM energization period θpwm, which is the period during which the PWM control is performed in the PWM cycle T in the switching control. The switching SW is controlled so as to include an on fixed energization period θon that maintains an on state longer than the PWM cycle T. Therefore, each of the control signal P and the control signal N is a PWM signal that turns on / off the switching SW at the duty ratio D and has a PWM cycle T, and a signal that keeps the switching SW on at all times during the on-fixed energization period θon. (Hereinafter, referred to as "on fixed energization signal") is included.

The PWM energization period θpwm does not have to be continuous and may be discontinuous. That is, in the period for performing switching control (half cycle ΔT), two or more PWM energization periods θpwm may be provided. However, in the present embodiment, only one on-fixed energization period θon is provided in the period for performing switching control (half cycle ΔT). For example, in the example shown in FIG. 2, the period for performing switching control (half cycle ΔT) is composed of one on-fixed energization period θon and two PWM energization periods θpwm.

In PWM control, the control unit 8 feedback-controls the drive current of the motor 2 by setting the duty ratio D of the PWM signal so that the phase current (drive current) Ip flowing through the motor 2 follows the target value Iref. You may. For example, the control unit 8 may perform the feedback control by performing PI control based on the difference value ΔI between the drive current Ip of the motor 2 and the target value Iref.

In this embodiment, the timing at which the on-fixed energization period θon is provided for the switching element SW is not particularly limited. For example, the control unit 8 may provide the switching element SW with an on-fixed energization period θon centered on a time point (ΔT / 2) of half the period of the half cycle ΔT for performing switching control. For example, when switching control is performed for a certain switching element SW at an electric angle of 0 to 180 degrees and the on-fixed energization period (phase width) θon is 30 degrees, the electric angle is 90 degrees. A range of ± 15 degrees around a certain position may be set as the on-fixed energization period.

Thus, one feature of the present embodiment, while changing the on fixed conducting period [theta] on, loss generated in the motor 2 (hereinafter, referred to as "motor loss".) Generated by P _M and the inverter 4 Loss (hereinafter. referred to as "inverter loss") losses sum of the P _IV (hereinafter, referred to as "total loss".) P _S to perform the minimum loss point tracking control is always searching for on fixed conduction period θon which minimizes Is. Total other words, a minimum loss point tracking control according to the present embodiment, in a state where driving the motor 2, so that the total loss P _S is minimized, while changing the on fixed conducting period θo as a parameter loss P _S is to switching control of the switching element SW to minimize.

Hereinafter, the total losses P _S according to the first embodiment will be described with reference to FIG. Figure 3 is a diagram showing an example of a trend for motor loss P _M, on a fixed conducting period θon the inverter loss P _IV and total losses P _S according to this embodiment.

The present inventors have found that as the on fixed conducting period θon increases, both the inverter loss P _IV motor loss P _M tends to increase was found that tends to decrease. As shown in FIG. 3, the loss on the vertical axis in the graph in which the horizontal axis on a fixed conducting period [theta] on, when plotting the motor loss P _M and the inverter loss P _IV, the on fixed within a predetermined range of conduction period [theta] on in point of total loss P _S is minimized (hereinafter, referred to as "minimum loss point".) exists. That is, the total losses P _S is within a predetermined range of on the fixed conducting period [theta] on, so that always there is a minimum loss point. Therefore, the control unit 8 constantly searches for the on-fixed energization period θon _min of the minimum loss point while changing the on-fixed energization period θon and performs switching control, so that even if the load fluctuation of the motor 2 occurs, the total loss it is possible to reduce the P _S.

Here, when the load of the motor 2 is constant, the DC power (hereinafter, referred to as "input power".) Input from the tendency and the power supply 1 of total losses P _S for on fixed conducting period θon the inverter 4 Pin The same tendency is shown. That is, when the load of the motor 2 is constant, the total loss P _S and on fixed conducting period θon as a minimum, and the on stationary conduction period θon the input power Pin is minimized, the same. Therefore, in the minimum power point tracking control, the control unit 8 according to the present embodiment changes the on-fixed energization period θon of the inverter 4 when the motor 2 is driven, and switches elements SW1 to minimize the input power Pin. Controls the ON state and OFF state of SW6.

Since the minimum loss point also fluctuates when the load of the motor 2 fluctuates, the response angular frequency ω _θ of the control system that changes the on-fixed energization period θon in the minimum loss point tracking control is assumed. It is set to a value larger than the frequency ω _L of the load fluctuation of the motor 2. The response angular frequency ω _θ of the second control system is a frequency for controlling the on-fixed energization period θon (control frequency of the on-fixed energization period θon). It is desirable that the assumed frequency ω _L of the load fluctuation of the motor 2 is the maximum frequency of the assumed load fluctuation of the motor 2.
Further, when the response angular frequency ω _θ is larger than the resonance angular frequency ωr (> ω _L ) of the PWM control control system when the load of the motor 2 fluctuates, the on-fixed energization period θon is in a transient state (unstable state) such as resonance. ) May be followed.

Therefore, the response angular frequency ω _θ may be set to a value smaller than the resonance angular frequency ωr. For example, the response angular frequency ω _θ is set so as to satisfy the following condition (1).
ω _L << ω _θ << ωr… (1)

An example of the schematic configuration of the control unit 8 according to the first embodiment will be described below with reference to FIG. The configuration of the control unit 8 described below will be described as an example of a configuration in which the minimum loss point tracking control and the PWM control are executed as the switching control.

The control unit 8 includes a current control unit 10, a minimum loss point tracking control unit 11, a carrier wave generation unit 12, a command value generation unit 13, and a control signal generation unit 14.

The current control unit 10 acquires the drive current Ip of the motor 2 from, for example, a current sensor (not shown) provided in the inverter 4. Further, the current control unit 10 reads the target value Iref from the storage unit (not shown) of the control unit 8. Then, the current control unit 10 calculates the difference ΔI between the drive current Ip and the target value Iref. The current control unit 10 calculates the first control command value S1 for bringing the difference ΔI closer to zero by executing the PI calculation for the calculated difference ΔI. Then, the current control unit 10 outputs the calculated first control command value S1 to the command value generation unit 13. The first control command value S1 is a signal whose voltage value is Vs1.

The minimum power point tracking control unit 11 calculates the current input power Pin (= Iin × Vin) by multiplying the input current Iin detected by the current detection unit 6 and the input voltage Vin detected by the voltage detection unit 7. To do. Then, the minimum power point tracking control unit 11 compares the calculated current input power Pin with the previous input power Pin, and adjusts the width of the on-fixed energization period θon according to the comparison result. For example, when the current input power Pin is equal to or greater than the previous input power Pin, the minimum power point tracking control unit 11 increases or decreases the width of the on-fixed energization period θo in a direction different from the previous adjustment. That is, when the width of the on-fixed energization period θo is increased in the previous adjustment, the minimum loss point tracking control unit 11 newly turns on a value reduced by a predetermined value from the current on-fixed energization period θon. When the fixed energization period θon is set and the width of the on fixed energization period θo is reduced in the previous adjustment, the value increased by a predetermined value from the current on fixed energization period θon is referred to as the new on fixed energization period θon. To do.
On the other hand, the minimum loss point tracking control unit 11 compares the calculated current input power Pin with the previous input power Pin, and if the current input power Pin is smaller than the previous input power Pin, the previous input power Pin is compared. On Increases or decreases the width of the fixed energization period θo in the same direction as the adjustment. That is, when the width of the on-fixed energization period θo is increased in the previous adjustment, the minimum loss point tracking control unit 11 newly turns on a value that is increased by a predetermined value from the current on-fixed energization period θon. When the fixed energization period θon is set and the width of the on fixed energization period θo is reduced in the previous adjustment, the value reduced by a predetermined value from the current on fixed energization period θon is referred to as the new on fixed energization period θon. To do. The minimum loss point tracking control unit 11 outputs the set new on-fixed energization period θon to the command value generation unit 13.

The carrier wave generation unit 12 generates a carrier wave CW which is a periodic signal (for example, a triangular wave signal) having a predetermined frequency. Then, the carrier wave generation unit 12 outputs the generated carrier wave CW to the control signal generation unit 14. For example, the carrier wave CW is a triangular wave or sawtooth wave signal having a voltage value of Vc.

The command value generation unit 13 always has a voltage value Von higher than the voltage value Vc of the carrier wave CW during the new on fixed energization period θon obtained by the minimum loss point tracking control unit 11, and the new on A signal that becomes the voltage value Vs1 of the first control command value in the period other than the fixed energization period θon is obtained as the final command value (second control command value) S2.

The control signal generation unit 14 generates a control signal based on the second control command value S2 acquired from the command value generation unit 13. For example, the control signal generation unit 14 compares the second control command value S2 acquired from the command value generation unit 13 with the carrier wave CW acquired from the carrier wave generation unit 12, and controls the second from the carrier wave CW. During the period when the amplitude (voltage value) of the command value is large, it becomes the first voltage (for example, high level) V1, and when the voltage value of the second control command value S2 is smaller than the carrier wave CW, the first voltage A control signal having a second voltage V2 (for example, a low level such as 0V) different from V1 is generated. Here, during the on-fixed energization period θon, the voltage value of the second control command value is always larger than that of the carrier wave CW (Von> Vc). Therefore, the control signal generated by the control signal generation unit 14 is always the first voltage V1 during the on-fixed energization period θon. In this way, the control unit 8 outputs the PWM signal to the switching element SW during the period other than the on-fixed energization period θon, but forcibly supplies the first voltage V1 to the switching element during the on-fixed energization period θon. Output to SW.

Next, the operation flow of the minimum loss point tracking control according to the first embodiment will be described with reference to FIG. FIG. 6 is a flow chart of the minimum loss point tracking control according to the first embodiment.

First, the control unit 8 drives the inverter 4 by outputting a control signal in which the on-fixed energization period θon is set to a preset initial value θ ₀ to the switching elements SW1 to SW6. Thus, in the on fixed conducting period [theta] on = initial value theta ₀ period, the inverter 4 when the switching element SW is controlled to the ON state, the motor 2 converts the input power Pin inputted from the power supply 1 to AC power Supply. As a result, the motor 2 is driven (step S101). The initial value θ ₀ is, for example, a reference value or design value obtained from a simulation, or a reference value obtained experimentally.

Next, the control unit 8 adds a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon while the motor 2 is being driven (step S102). Here, the minute period Δθon is set in advance, and is the amount of change that changes the on-fixed energization period θon for each control cycle in the minimum loss point tracking control. The increase / decrease flag F determines whether to increase or decrease the on-fixed energization period θon when the on-fixed energization period θon is changed in the minimum loss point tracking control. For example, if the increase / decrease flag F is "+1", the on-fixed energization period θon is increased, and if the increase / decrease flag F is "-1", the on-fixed energization period θon is decreased. The initial value of the increase / decrease flag F is set in step S101, and is set to "+1" as the initial value in the present embodiment. However, the initial value of the increase / decrease flag F may be "-1".

The current detection unit 6 detects the input current Iin input from the power supply device 1 to the inverter 4, and outputs the detected input current Iin to the control unit 8. Further, the voltage detection unit 7 detects the input voltage Vin input from the power supply device 1 to the inverter 4, and outputs the detected input voltage Vin to the control unit 8 (step S103).

The control unit 8 calculates the current input power Pin (= Iin × Vin) by multiplying the input current Iin acquired from the current detection unit 6 and the input voltage Vin acquired from the voltage detection unit 7 (step). S104).

When the control unit 8 calculates the current input power Pin, the control unit 8 compares the calculated current input power Pin with the input power Pin calculated in the previous control cycle (step S105). In order to prevent the explanation from becoming complicated, the input power Pin calculated in the previous control cycle is referred to as the input power Pre. The initial value of the input power Pref is set in step S101, and is set to "0" in this embodiment.

The control unit 8 compares the current input power Pin with the previous input power Pre, and when the current input power Pin is smaller than the previous input power Pref (Pin <Pref), the sign of the increase / decrease flag F is Not going to change. Then, the control unit 8 sets the current input power Pin as the previous input power Pref (step S107), and returns to the process of step S102. Therefore, in the process of step S102, the control unit 8 sets a new on-fixed energization period θon by adding a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon. Therefore, the control unit 8 outputs a control signal having the new on-fixed energization period θon to the switching element SW.

On the other hand, the control unit 8 compares the current input power Pin with the previous input power Pref, and when the current input power Pin is equal to or greater than the previous input power Pref (Pin ≧ Pref), the increase / decrease flag F Invert the sign of (step S107). Then, the control unit 8 sets the current input power Pin as the previous input power Pref (step S106), and returns to the process of step S102. Therefore, in the process of step S102, the control unit 8 sets a new on-fixed energization period θon by adding a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon. Therefore, the control unit 8 outputs a control signal having the new on-fixed energization period θon to the switching element SW.

In this way, by repeating steps S102 to S107, the control unit 8 sets the on-fixed energization period θon as a parameter, and increases or decreases the on-fixed energization period θon by a minute period Δθon while increasing or decreasing the input power Pin from the previous time. The inverter 4 is switched and controlled so as to be smaller than the value of. As a result, the control unit 8 can search for the minimum loss point while increasing or decreasing the on-fixed energization period θon. As a result, the motor system A has a minimum loss regardless of the rotation speed of the motor 2, the temperature of the motor 2 and the switching elements SW1 to 6, the output voltage of the power supply device 1, the individual variation of the motor 2 and the switching elements SW1 to 6, and the like. The motor 2 can be continued to operate.

In the first embodiment, the control unit 8 sets the initial conditions in the process of step S101 at the start of the minimum loss point tracking control, and then sets the on-fixed energization period θon (initial value θ ₀ ) for a minute period Δθon. × After adding the increase / decrease flag F (step S102), the input current Iin and the input voltage Vin were acquired (step S103), and the input power Pin was calculated (step S104), but the present invention is not limited thereto. For example, at the start of the minimum loss point tracking control, the control unit 8 may execute the processes of steps S103 and S104 after performing the process of step S101 without performing the process of step S102. In this case, the control unit 8 performs the process of step S102 after the process of step S107.

Specifically, as shown in FIG. 7, first, the control unit 8 sets the initial conditions. That is, the control unit 8 drives the inverter 4 by outputting the control signal in which the on-fixed energization period θon is set to the preset initial value θ ₀ to the switching elements SW1 to SW6, as in the processing of the switch 101. To do. Further, the control unit 8 sets the previous input power Pref to the initial value “0” and the increase / decrease flag F to the initial value “+1” (step S201).

After the initial conditions are set, the current detection unit 6 detects the input current Iin input from the power supply device 1 to the inverter 4, and outputs the detected input current Iin to the control unit 8. Further, the voltage detection unit 7 detects the input voltage Vin input from the power supply device 1 to the inverter 4, and outputs the detected input voltage Vin to the control unit 8 (step S202).

The control unit 8 calculates the input power Pin (= Iin × Vin) by multiplying the input current Iin acquired from the current detection unit 6 and the input voltage Vin acquired from the voltage detection unit 7 (step S203). ..

When the control unit 8 calculates the current input power Pin, the calculated current input power Pin is compared with the previously calculated input power Pre (step S204), and the current input power Pin is the previous input power. If it is smaller than Pref (Pin <Pref), the sign of the increase / decrease flag F is not changed. Then, the control unit 8 sets the current input power Pin as the previous input power Pref (step S206). On the other hand, the control unit 8 compares the current input power Pin with the previous input power Pref, and when the current input power Pin is equal to or greater than the previous input power Pref (Pin ≧ Pref), the increase / decrease flag F Invert the sign of (step S205). Then, the control unit 8 sets the current input power Pin as the previous input power Pref (step S206). After that, the control unit 8 adds a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon (step S207), and returns to the process of step S202.

(Second Embodiment)
The motor system B according to the second embodiment will be described below. Motor system B according to the second embodiment differs from the motor system A according to the first embodiment, a method for determining the total loss P _S is different at different points. In the drawings, the same or similar parts may be designated by the same reference numerals to omit duplicate explanations.

FIG. 8 is a diagram showing an example of a schematic configuration of the motor system A according to the first embodiment.
As shown in FIG. 8, the motor system B includes a power supply device 1, a motor 2, and a motor drive device 3B. The motor drive device 3B includes an inverter 4 and an inverter control unit 5B. The inverter control unit 5B includes an AC power detection unit 20, an inverter loss calculation unit 21, and a control unit 8B.

The AC power detection unit 20 has a phase current (drive current) flowing through the motor 2 by, for example, a current transformer (CT) provided between the output terminal N3 and the coil Lu and between the output terminal N5 and the coil Lw. Ip is detected. However, the AC power detection unit 20 is not particularly limited as long as it can detect the phase current (drive current) Ip flowing through the motor 2.

The AC power detection unit 20 detects the AC voltage Vmot of each phase applied to the motor. The AC power detection unit 20 calculates the power (hereinafter, referred to as “motor input power”) Pmot input to the motor 2 by multiplying the drive current Ip and the AC voltage Vmot. Then, the AC power detection unit 20 outputs the calculated motor input power Pmot to the control unit 8B. Further, the AC power detection unit 20 outputs the detected drive current Ip information to the inverter loss calculation unit 21.

Inverter loss calculation unit 21 based on the acquired information of the drive current Ip from the AC power detection unit 20, obtains the inverter loss P _IV. Then, the inverter loss calculation unit 21 outputs the obtained inverter loss _PIV to the control unit 8B. Here, the inverter loss calculation unit 21, driving long as the information of the current Ip to seek inverter loss P _IV, is not particularly limited to the method of obtaining the driving current based on calculations and tables, for example preset from information Ip may be obtained inverter loss _{P IV.} These formulas and tables, for example, as can be determined inverter loss P _IV is based on the drive current Ip, it may be determined experimentally or theoretically. In the case of using a preset table, and the drive current Ip, advance a lookup table and an inverter loss P _IV associated with each driving current Ip in the storage unit of the control unit 8B (not shown) It may be remembered. Then, inverter loss calculation unit 21, the inverter loss P _IV corresponding to the drive current Ip obtained from the AC power detection unit 20 obtained from the look-up table, and outputs the acquired inverter loss P _IV to the control section 8B May be good. For example, inverter loss calculating section 21 may obtain the inverter loss P _IV from the acquired information of the drive current Ip from the AC power detector 20 using known techniques.

Similar to the control unit 8, the control unit 8B controls the ON state and the OFF state of the switching elements SW1 to SW6, thereby converting the DC power from the power supply device 1 into AC power in the inverter 4. For example, in the control unit 8B, the switching elements SW1 to SW6 are turned on and off so that the phases of the currents flowing through the U-phase coil Lu, the V-phase coil Lv, and the W-phase coil Lw are shifted by 120 degrees. Performs switching control to control the state.
At this time, the control section 8B, in each of the switching elements SW1 to SW6, on such that the total losses P _S while changing the on fixed conducting period θon a period for maintaining the switching element SW in the ON state becomes minimum fixed The minimum loss point tracking control that controls the energization period θon is executed.

For example, the control section 8B includes a motor input power Pmot AC power detector 20 is calculated, inverter loss value calculation unit 21 is the sum of the inverter loss P _IV obtained (addition value) obtaining the Pc. Here, when the load of the motor 2 is constant, the tendency of the total loss P _S with respect to the on-fixed energization period θon and the tendency of the added value Pc show the same tendency. That is, when the load of the motor 2 is constant, the on-fixed energization period θon that minimizes the total loss P _S and the on-fixed energization period θon that minimizes the added value Pc are the same. Therefore, the control unit 8B according to the second embodiment obtains the addition value Pc as the total loss Ps, and adds while changing the on-fixed energization period θon of the inverter 4 when the motor 2 is driven in the minimum loss point tracking control. The ON state and OFF state of the switching elements SW1 to SW6 are controlled so that the value Pc is minimized. Since the switching control of the control unit 8B for the switching elements SW1 to SW6 is the same as that of the first embodiment, the description thereof will be omitted.

Next, the operation flow of the minimum loss point tracking control according to the second embodiment will be described with reference to FIG. FIG. 9 is a flow chart of the minimum loss point tracking control according to the second embodiment.

First, the control unit 8B drives the inverter 4 by outputting a control signal in which the on-fixed energization period θon is set to a preset initial value θ ₀ to the switching elements SW1 to SW6. Thus, in the on fixed conducting period [theta] on = initial value theta ₀ period, the inverter 4 when the switching element SW is controlled to the ON state, the motor 2 converts the input power Pin inputted from the power supply 1 to AC power Supply. As a result, the motor 2 is driven (step S301).

Next, the control unit 8B adds a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon while the motor 2 is being driven (step S302). The AC power detection unit 20 detects the AC voltage Vmot of each phase applied to the motor. Then, the AC power detection unit 20 calculates the motor input power Pmot input to the motor 2 by multiplying the drive current Ip and the AC voltage Vmot. Further, inverter loss calculation unit 21 based on the acquired information of the drive current Ip from the AC power detection unit 20, obtains the inverter loss _{P IV} (step S303). The control unit 8B determines a motor input power Pmot AC power detector 20 is calculated, the sum value Pc of inverter loss calculating section 21 adds the inverter loss _{P IV} obtained (step S304).

When the control unit 8B calculates the current addition value Pc, the control unit 8B compares the calculated current addition value Pc with the addition value Pc calculated in the previous control cycle (step S305). In order to prevent the explanation from becoming complicated, the added value Pc calculated in the previous control cycle is referred to as an input power Pref. The initial value of the input power Pref is set in step S301, and is set to "0" in this embodiment.

The control unit 8B compares the current added value Pc with the previous input power Pref, and when the current added value Pc is smaller than the previous input power Pref (Pc <Pref), the sign of the increase / decrease flag F is Not going to change. Then, the control unit 8B sets the current addition value Pc as the previous input power Pref (step S307), and returns to the process of step S302. Therefore, in the process of step S302, the control unit 8B sets a new on-fixed energization period θon by adding a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon. Therefore, the control unit 8B outputs a control signal having the new on-fixed energization period θon to the switching element SW.

On the other hand, the control unit 8B compares the current added value Pc with the previous input power Pref, and when the current added value Pc is equal to or greater than the previous input power Pref (Pc ≧ Pref), the increase / decrease flag F Invert the sign of (step S306). Then, the control unit 8B sets the current addition value Pc as the previous input power Pref (step S307), and returns to the process of step S302. Therefore, in the process of step S302, the control unit 8B sets a new on-fixed energization period θon by adding a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon. Therefore, the control unit 8B outputs a control signal having the new on-fixed energization period θon to the switching element SW.

In this way, by repeating steps S302 to S307, the control unit 8B increases or decreases the on-fixed energization period θon by a minute period Δθon from the previous on-fixed energization period θon while increasing or decreasing the added value Pc last time. The inverter 4 is switched and controlled so as to be smaller than the value of. As a result, the control unit 8B can search for the minimum loss point while increasing or decreasing the on-fixed energization period θon. As a result, the motor system A has a minimum loss regardless of the rotation speed of the motor 2, the temperature of the motor 2 and the switching elements SW1 to 6, the output voltage of the power supply device 1, the individual variation of the motor 2 and the switching elements SW1 to 6, and the like. The motor 2 can be continued to operate.

In the second embodiment, the control unit 8B sets the initial conditions in the process of step S301 at the start of the minimum loss point tracking control, and then sets the on-fixed energization period θon (initial value θ ₀ ) for a minute period Δθon. × after adding the decrease flag F (step S302), the acquisition of the motor input power Pmot and inverter loss _{P IV} (step S303), were subjected to calculation of the sum Pc (step S304), the present invention is not limited thereto .. For example, at the start of the minimum loss point tracking control, the control unit 8B may execute the processes of steps S303 and S104 after performing the process of step S301 without performing the process of step S302. In this case, the control unit 8B performs the process of step S302 after the process of step S307.

Specifically, as shown in FIG. 10, first, the control unit 8B sets the initial conditions. That is, the control unit 8B drives the inverter 4 by outputting the control signal in which the on-fixed energization period θon is set to the preset initial value θ ₀ to the switching elements SW1 to SW6, as in the process of step S301. To do. Further, the control unit 8B sets the previous input power Pref to the initial value “0” and the increase / decrease flag F to the initial value “+1” (step S401).

After the initial conditions are set, the AC power detection unit 20 calculates the motor input power Pmot input to the motor 2 by calculating the drive current Ip and the AC voltage Vmot. Further, inverter loss calculation unit 21 based on the acquired information of the drive current Ip from the AC power detection unit 20, obtains the inverter loss _{P IV} (step S402).

Control section 8B calculates a motor input power Pmot AC power detector 20 is calculated, the sum value Pc of inverter loss calculating section 21 adds the inverter loss _{P IV} obtained (step S403).

When the control unit 8B calculates the current added value Pc, the calculated current added value Pc is compared with the previously calculated input power Pref (step S404), and the current added value Pc is the previous input power. If it is smaller than Pref (Pc <Pref), the sign of the increase / decrease flag F is not changed. Then, the control unit 8B sets the current addition value Pc as the previous input power Pref (step S406). On the other hand, the control unit 8B compares the current added value Pc with the previous input power Pref, and when the current added value Pc is equal to or greater than the previous input power Pref (Pc ≧ Pref), the increase / decrease flag F Invert the sign of (step S405). Then, the control unit 8B sets the current addition value Pc as the previous input power Pref (step S406). After that, the control unit 8B adds a minute period Δθon × increase / decrease flag F to the current on-fixed energization period θon (step S407), and returns to the process of step S402.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design and the like within a range not deviating from the gist of the present invention are also included.

(Modification example 1)
In the first embodiment or the second embodiment, the range of the on-fixed energization period θon to be changed may be limited in the minimum loss point tracking control. For example, the control unit 8 or the control unit 8B sets the on-fixed energization period θon in the minimum loss point tracking control within a range (θon) between the minimum value θon _MIN (minimum value) and the maximum value θon _MAX (maximum value). _It may be changed within _MIN ≤ θon ≤ θon _MAX ).

(Modification 2)
In the first embodiment or the second embodiment, the motor system may include a first temperature sensor that measures the temperature Tsw of the switching elements SW1 to SW6. Then, when the temperature Tsw measured by the first temperature sensor becomes equal to or higher than the preset first threshold value Tth1 in the minimum loss point tracking control, the control unit 8 or the control unit 8B raises the temperature. The on-fixed energization period θon may be forcibly increased until Tsw becomes less than the first threshold value Tth1. For example, even if the control unit 8 or the control unit 8B performs the minimum loss point tracking control, when the temperature Tsw becomes equal to or higher than the first threshold value Tth1, the on-fixed energization period θon is forcibly set as an interrupt process. It may be increased. As a result, the loss (inverter loss) due to the switching elements SW1 to SW6 is reduced, and the control unit 8 or the control unit 8B can prevent the switching elements SW1 to SW6 from failing due to heat generation. As a method of forcibly increasing the on-fixed energization period θon, for example, there is a method of forcibly fixing the sign of the increase / decrease flag F to “+1”.

(Modification 3)
In the first or second embodiment, the motor system may comprise a second temperature sensor for measuring the temperature T _M of the motor 2. The temperature _{T M} of the motor 2, for example, a coil Lu, Lv, each temperature of Lw. Then, the control unit 8 or the control unit 8B, at the minimum loss point tracking control, if it becomes the second threshold value Tth2 or the said second temperature T _M measured by the temperature sensor is set in advance, the temperature T _M may be forcibly reduced on fixed conducting period θon to below a second threshold Tth2. For example, the control unit 8 or the control unit 8B can also be carried out minimum loss point tracking control, if the temperature T _M is equal to or higher than the second threshold value Tth2 is forced on a fixed conducting period θon as interrupt processing May be reduced. As a result, the motor loss is reduced, and the control unit 8 or the control unit 8B can prevent the motor 2 from failing due to the heat generated by the coils Lu, Lv, and Lw. As a method of forcibly reducing the on-fixed energization period θon, for example, there is a method of forcibly fixing the sign of the increase / decrease flag F to “-1”.

(Modification example 4)
In the first embodiment or the second embodiment, the motor system may include both the first temperature sensor and the second temperature sensor. Then, the control unit 8 or the control unit 8B, the temperature Tsw is the first threshold value Tth1 or more, and, if the temperature _{T M} becomes the second threshold value Tth2 or more, so that the driving current of the motor 2 is reduced It may be controlled to. For example, the control unit 8 or the control unit 8B lowers the target value of the drive current of the motor 2. As a result, both the inverter loss and the motor loss are reduced, and failure due to heat generation between the switching elements SW1 to SW6 and the motor 2 can be prevented.

(Modification 5)
In the first embodiment, the control unit 8 acquires the input power Pin by multiplying the input current Iin detected by the current detection unit 6 and the input voltage Vin detected by the voltage detection unit 7. The invention is not limited to this. That is, the control unit 8 only needs to be able to acquire the input power Pin, and the acquisition method is not particularly limited. For example, the control unit 8 may acquire the input power Pin by the power sensor provided on the connection line L1. Further, the control unit 8 may acquire the input power Pin by calculating the input power Pin from the drive current of the motor 2, the conversion efficiency of the inverter 4, and the like.

(Modification 6)
In the first embodiment or the second embodiment, the control unit 8 or the control unit 8 has the command value generation unit 13 always during the new on-fixed energization period θon obtained by the minimum loss point tracking control unit 11. A signal that has a voltage value Von higher than the voltage value Vc of the carrier wave CW and a voltage value Vs1 of the first control command value in a period other than the new on-fixed energization period θon is finally commanded. It was obtained as a value (second control command value) S2, but is not limited to this. For example, as shown in FIG. 11, the control unit 8 may individually generate a PWM signal and an on-fixed energization signal and output them to the switching element SW.
For example, as shown in FIG. 11, the control unit 8 includes a current control unit 10, a carrier wave generation unit 12, a minimum loss point tracking control unit 110, a PWM signal generation unit 140, and a selection unit 150.

The minimum power point tracking control unit 110 calculates the current input power Pin (= Iin × Vin) by multiplying the input current Iin detected by the current detection unit 6 and the input voltage Vin detected by the voltage detection unit 7. To do. Then, the minimum loss point tracking control unit 110 compares the calculated current input power Pin with the previous input power Pin, and if the current input power Pin is larger than the previous input power Pin, the increase / decrease flag is used. The sign of F is inverted, Δθon × increase / decrease flag F is added to the current on-fixed energization period θon, and an on-fixed energization signal having a first voltage V1 is always generated for a new on-fixed energization period θon. On the other hand, the minimum loss point tracking control unit 110 compares the calculated current input power Pin with the previous input power Pin, and if the current input power Pin is smaller than the previous input power Pin, the increase / decrease flag Without changing the sign of F, Δθon × increase / decrease flag F is added to the current on-fixed energization period θon to always generate an on-fixed energization signal having the first voltage V1 for a new on-fixed energization period θon. Then, the minimum loss point tracking control unit 110 outputs the generated on-fixed energization signal to the selection unit 150.

The PWM signal generation unit 140 compares the first control command value S1 generated by the current control unit 10 with the carrier wave CW acquired from the carrier wave generation unit 12, and the first control command value S1 from the carrier wave CW. During the period when the voltage value of is large, it becomes the first voltage V1, and when the voltage value of the first control command value S1 is smaller than the carrier wave CW, it becomes the second voltage V2 which is different from the first voltage V1. Generates a PWM signal. Then, the PWM signal generation unit 140 outputs the generated PWM signal to the selection unit 150.

When the selection unit 150 acquires the on-fixed energization signal of the voltage value V1 from the minimum loss point tracking control unit 110, the selection unit 150 outputs the on-fixed energization signal as a control signal to the switching element SW. On the other hand, when the selection unit 150 does not acquire the on-fixed energization signal of the voltage value V1 from the minimum loss point tracking control unit 110, the selection unit 150 outputs the PWM signal acquired from the PWM signal generation unit 140 to the switching element SW as a control signal. .. In this way, when the selection unit 150 acquires the on-fixed energization signal of the voltage value V1 from the minimum loss point tracking control unit 110, the selection unit 150 selects the on-fixed energization signal as the control signal and uses the on-fixed energization signal. If not acquired, the PWM signal is selected as a control signal and output to the switching element SW.
The methods described in Modifications 7 and 11 can be applied to the control unit 8B according to the second embodiment. However, in that case, the minimum loss point tracking control unit 110 of the control unit 8B compares the current addition value Pc with the previous addition value.

As described above, the present inventors have discovered that as the on fixed conducting period θon increases, both the inverter loss P _IV motor loss P _M tends to decrease tends to increase, the total losses P _S It was found that there is a minimum loss point with the on-fixed energization period θon as a parameter. The apparatus 3 according to the present embodiment, which has been made based on these findings, while changing the on fixed conduction period θon switching element SW1~SW6 constituting the inverter 4, the motor loss P _M and a control unit 8 or the control unit 8B total loss _{P S} is switching control of the switching element SW1~SW6 so as to minimize that an inverter loss _{P IV.}

According to such a configuration, even when the load change of the motor 2 occurs, it is possible to maintain the total losses P _S to always minimized losses. Therefore, the loss generated in the motor system due to the load fluctuation of the motor 2 can be reduced.

For example, the control unit 8 may change the ON fixed energization period θon of the switching elements SW1 to SW6 so that the input power Pin input from the power supply device 1 to the inverter 4 is minimized. For example, the control section 8B includes a motor input power Pmot AC power detector 20 is calculated, inverter loss value calculation unit 21 is the sum of the inverter loss P _IV obtained (addition value) switched to Pc is minimized The on-fixed energization period θon of the elements SW1 to SW6 may be changed.
Thus, on fixed conducting period θon is not a fixed value, a variable value which varies as a function of total losses P _S.

Further, the control unit 8 or the control unit 8B may have a configuration in which the drive current of the motor 2 is feedback-controlled so as to follow the target value. Then, in the control unit 8 or the control unit 8B, the control frequency of the on-fixed energization period θon is smaller than the resonance frequency of the feedback control at the time of load fluctuation and larger than the frequency of the load fluctuation of the motor 2. May be good.

According to such a configuration, the on-fixed energization period θon set in the minimum loss point tracking control can sufficiently respond to and follow the load fluctuation of the motor 2 without following the transition state such as resonance.

Further, the motor system A or the motor system B may further include a first temperature sensor for measuring the temperature Tsw of the switching elements SW1 to SW6. Then, the control unit 8 or the control unit 8B may forcibly reduce the on-fixed energization period θon when the temperature Tsw measured by the first temperature sensor becomes equal to or higher than the first threshold value Tth1. ..

According to such a configuration, the inverter loss is reduced, and it is possible to prevent the switching elements SW1 to SW6 from failing due to heat generation.

Further, the motor system A or the motor system B may further include a second temperature sensor for measuring the temperature of the motor 2. Then, the control unit 8 or the control unit 8B, when the temperature T _M measured by the second temperature sensor is equal to or greater than the second threshold value Tth2, even forcibly increasing an on fixed conduction period θon Good.

According to such a configuration, the motor loss can be reduced, and it is possible to prevent the motor 2 from failing due to heat generation of the coils Lu, Lv, and Lw.

Note that all or part of the control unit 8 or the control unit 8B described above may be realized by a computer. In this case, the computer may include a processor such as a CPU and GPU and a computer-readable recording medium. Then, a program for realizing all or a part of the functions of the control unit 8 or the control unit 8B on the computer is recorded on the computer-readable recording medium, and the program recorded on the recording medium is recorded on the processor. It may be realized by loading and executing. Here, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or a client in that case. Further, the above program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system. It may be realized by using a programmable logic device such as FPGA.

A, B Motor system 1 Power supply 2 Motor 3 Motor drive 4 Inverter (power converter)
8,8B control unit

Claims (5)

A motor system that drives a motor by converting DC power from a power supply device into AC power by a power conversion device and supplying it to the motor.
A control unit for controlling an on state and an off state of the switching element constituting the power conversion device is provided.
The control unit minimizes the total loss including the loss generated by the motor and the loss generated by the power converter while changing the on-fixed energization period, which is the period during which the switching element is on. A motor system including a control unit that executes a minimum loss point tracking control that controls an on-fixed energization period. The motor system according to claim 1, wherein the control unit controls the on-fixed energization period so that the DC power is minimized in the minimum loss point tracking control. The control unit executes the minimum loss point tracking control and the PWM control for turning on / off the switching element at a predetermined cycle for the switching element, and in the minimum loss point tracking control, the cycle is longer than the predetermined cycle. The motor system according to claim 1 or 2, characterized in that a long on-fixed energization period is provided. A first temperature sensor for measuring the temperature of the switching element is further provided.
Claims 1 to 3 include that the control unit forcibly increases the on-fixed energization period when the temperature measured by the first temperature sensor becomes equal to or higher than the first threshold value. The motor system according to any one of the above. A second temperature sensor for measuring the temperature of the motor is further provided.
Claims 1 to 3 are characterized in that the control unit forcibly reduces the on-fixed energization period when the temperature measured by the second temperature sensor becomes equal to or higher than the second threshold value. The motor system according to any one of the above.

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