JP5252213B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device, and more particularly to a power supply device that has a flyback transformer and supplies power to a plurality of load circuits connected to a secondary side in a state where the primary side and the secondary side are insulated.

Conventionally, a flyback type power supply device including a flyback transformer is known as an insulating switching power supply (see, for example, Patent Document 1).
In this flyback type power supply device, a plurality of load circuits can be simultaneously connected to the secondary side, a tertiary coil is provided for controlling the output voltage on the secondary side, and the load is connected to the tertiary coil. The circuit is configured so that the power consumption satisfies the power consumption condition of the load circuit connected to the secondary side, and detects the voltage of the current flowing through the load circuit connected to the tertiary coil (control coil). As a result, the output voltage was controlled.
JP 2004-343946 A

By the way, the flyback type power supply apparatus has a configuration suitable for obtaining a plurality of insulated outputs at low cost, but has a problem that cross regulation is not good because there is only one system of feedback.
In other words, the system to which feedback is made is stabilized, but the characteristics of each output system are made the same for other systems due to differences in winding ratio, coupling rate, wiring resistance (copper loss), iron loss, etc. It was difficult.

As a technique for solving this problem, a method has been proposed in which an LDO (Low Drop Out linear regulator) is provided on the secondary side for each phase to stabilize the voltage or suppress fluctuations in the load.
However, when the number of output systems increases, power consumption increases unnecessarily, and problems such as a complicated circuit configuration and increased component costs due to an increase in the number of components have occurred.

Also, variations in diode forward voltage Vf for rectifying the output current for each output system (depending on individual differences, ambient temperature, current value, etc.), transformer leakage inductance and winding resistance of flyback transformer, output when rectifier is off There is a possibility that the cross regulation may be lowered due to a non-coupling state or the like.
On the other hand, in order to reduce the difference in output voltage for each output system, a method of switching at a low frequency using a large transformer is effective. However, there is a contradictory direction from the recent demand for miniaturization, and it is desired to obtain stable regulation with a small transformer.
Accordingly, an object of the present invention is to reduce the difference in output voltage among a large number of output systems and improve cross regulation even when a small flyback transformer is used while suppressing power consumption and the number of parts. It is an object of the present invention to provide a flyback type power supply device capable of achieving the above.

In order to solve the above problems, a first aspect of the present invention includes a multi-output type flyback transformer having a control coil and a bleeder resistor connected to the control coil, and a plurality of outputs of the flyback transformer. A load is connected to each of the plurality of loads, and an output voltage of the flyback transformer is supplied to the plurality of loads, and a primary side of the flyback transformer is changed based on a feedback voltage value that changes according to the voltage of the bleeder resistor. In the power supply apparatus including an adjustment circuit that controls an input voltage and adjusts an output voltage value to a constant value, the plurality of loads are driven by repeatedly inputting a load drive control signal, and each of the loads is The load amount at the time of driving is the same, and based on the presence or absence of the load drive control signal, a change in the number of the driven loads is detected, To compensate for variations in the output voltage caused by the change of the number of loads, characterized by comprising a feedback value adjusting circuit for adjusting the feedback current inputted to the adjusting circuit.
According to the above configuration, since the plurality of loads are driven by repeatedly inputting the load drive control signal, the number of simultaneously driven loads can be grasped by the presence or absence of the load drive control signal. Since the load has the same load amount at the time of driving, the fluctuation amount of the output voltage due to the fluctuation of the load amount can be estimated from the fluctuation of the number of simultaneously driven loads. Therefore, the feedback value adjustment circuit detects a change in the number of driven loads based on the presence or absence of the load drive control signal, and is caused by the change in the number of loads corresponding to the load amount at the time of driving each load. The feedback voltage value input to the adjustment circuit is adjusted so as to compensate for fluctuations in the output voltage.

According to a second aspect of the present invention, in the first aspect, the load is a motor drive circuit corresponding to any phase of a synchronous multiphase motor, and the load drive control signal is transmitted from the primary side to the secondary side. The PWM control signal is supplied to each of the motor drive circuits in a corresponding phase, and the feedback value adjustment circuit detects the PWM control signal on the primary side.
According to the above configuration, when the synchronous multiphase motor is driven, the feedback value adjustment circuit detects the PWM control signal on the primary side, and drives due to fluctuations in the rotational speed of the synchronous multiphase motor. Fluctuations in the number of motor drive circuits are detected based on the presence or absence of a PWM control signal, and fluctuations in the output voltage of the flyback transformer are suppressed.

According to a third aspect of the present invention, in the first or second aspect, the power conversion switching element is connected to a primary coil of the flyback transformer, and the number of the driven loads is the smallest. It is divided into a load state, a high load state having the largest number of driven loads, and an intermediate load state between them, and in the intermediate load state, the switching in the low load state and the high load state is performed. The switching element is driven at a predetermined switching frequency lower than a predetermined switching frequency of the element.
According to the above configuration, in the middle load state where the load variation range is large, the switching element is driven at a predetermined switching frequency lower than the predetermined switching frequency of the switching element in the low load state and the high load state.

According to the first aspect of the present invention, the feedback value adjustment circuit detects a change in the number of driven loads based on the presence / absence of a load drive control signal, and corresponds to the load amount at the time of driving each load. The feedback voltage value input to the adjustment circuit is adjusted so as to compensate for output voltage fluctuations due to fluctuations in the number of loads, so the output voltage of the flyback transformer due to fluctuations in the number of loads being driven Fluctuations can be suppressed, and the difference in output voltage between output systems can be reduced to improve cross regulation, so that it is easy to use a small flyback transformer in a flyback power supply device.
Furthermore, since the number of fluctuating loads is detected by using a load drive control signal necessary for load drive control, there is no need to newly provide a circuit for detection, thereby suppressing an increase in component costs. Can do.

  According to the second aspect of the present invention, in addition to the effect of the first aspect, the effective load state of the synchronous multiphase motor is detected on the primary side and supplied to the synchronous multiphase motor according to the detection result. Therefore, even when the rotational speed of the synchronous multiphase motor fluctuates greatly, it can be driven stably.

  According to the third aspect of the present invention, in addition to the effects of the first aspect or the second aspect, in the middle load state where the load amount fluctuates, the switching element is lower than the predetermined switching frequency in the low load state and the high load state. Since the switching element is driven at a low predetermined switching frequency, even when a rectifying diode is provided on the secondary side, the number of on / off times of the rectifying diode can be reduced, and the influence of forward voltage is reduced. In this way, it is possible to reliably absorb transient load fluctuations and obtain a more stable output voltage.

Next, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram of a schematic configuration of the present invention.
The power supply device 10 includes a flyback transformer 11 and converts the primary-side input voltage Vin input from the power supply 12 into a predetermined output voltage Vout (= Vout1, Vout2,...) And is connected to the secondary side. The power converter 14 that outputs to the plurality of load circuits 13-1, 13-2,..., And the entire drive state (= corresponding to the total load amount) are detected. A drive state detector 15 for controlling the output voltage Vout according to the drive state of the entire load from the detection circuit and the bleeder resistance value and the PWM converter oscillator for power conversion to adjust the feedback voltage for controlling the output voltage Vout And an adjustment value control unit 16 for adjusting the frequency.

Here, the plurality of load circuits 13-1, 13-2,... Are driven by repeatedly inputting the load drive control signal, and each load circuit 13-1, 13-2,. The load is the same.
Therefore, the drive state detector 15 determines the overall drive state of the load circuits 13-1, 13-2,..., That is, the load circuit 13- 1, 13-2,... The total load amount can be predicted, which is equivalent to the detection of the entire load amount.
Further, the adjustment value control unit 16 detects a change in the number of driven load circuits based on the presence / absence of a load drive control signal, and drives each load circuit 13-1, 13-2,. For PWM control for bleeder resistance value and power conversion to adjust the feedback voltage so as to compensate the fluctuation of the output voltage Vout due to the fluctuation of the number of driven load circuits based on the amount of load at the time The frequency of the oscillator is adjusted.
In the above configuration, the flyback transformer 11 is provided with a control coil (tertiary coil). A bleeder resistor is connected to the control coil, and the flyback transformer 11 is based on a feedback voltage that changes according to the voltage of the bleeder resistor. The output voltage Vout to the plurality of load circuits 13-1, 13-2,... Connected to the flyback transformer 11 is adjusted.

According to the above configuration, the power conversion unit 14 converts the primary-side input voltage Vin input from the power supply 12 into the predetermined output voltage Vout (= Vout1, Vout2,...) And is connected to the secondary side. Output to a plurality of load circuits 13-1, 13-2,.
In parallel with this, the drive state detection unit 15 performs a plurality of load circuits 13-1, 13-2,... Based on fluctuations in the number of load circuits driven simultaneously according to the presence or absence of the load drive control signal. It detects as a drive state, and outputs a detection result to the adjustment value control part 16.
Thereby, the adjustment value control unit changes the output voltage Vout according to the drive state of the entire load, which is the detection result output from the drive state detection unit 15, that is, according to the variation in the number of load circuits actually in the drive state. In order to adjust the feedback voltage for control, the bleeder resistance value and the frequency of the oscillator for PWM control for power conversion are adjusted.

  Therefore, the entire load circuits 13-1, 13-2,... Are driven so as to compensate for fluctuations in the output voltage Vout due to fluctuations in the number of load circuits 13-1, 13-2,. Since the feedback voltage is appropriately adjusted according to the state, the difference of the output voltage for each output system can be reduced, and as a result, the cross regulation can be improved.

FIG. 2 is a schematic configuration diagram of a motor driving device using the power supply device of the embodiment.
The motor drive device 20 is a device that drives an electric motor in an electric vehicle or a hybrid vehicle, and includes a battery 12 that is a power source, a smoothing capacitor 22 that smoothes a DC power supplied from the battery 12, and a motor. A controller 23 that centrally controls the drive device 20, an inverter circuit 24 having a plurality of IGBTs (Insulated Gate Bipolar Transistors), and six motor drive control signals (load drive control signals) MDC described later are input. An IGBT driver unit 25 for driving the IGBT constituting the inverter circuit 24, a three-phase AC motor 26 driven by the inverter circuit 24, and a current sensor 27-U for detecting a driving current of each phase of the three-phase AC motor 26; And it includes a 7-V, 27-W, a.

The controller 23 is configured as a microcomputer, and includes an MPU, a ROM, and a RAM (not shown). The MPU performs various processes using the RAM as a work area based on a control program stored in the ROM in advance.
The inverter circuit 24 includes IGBT series circuits 24U, 24V, and 24W having two IGBTs connected in series, and the IGBT series circuits 24U, 24V, and 24W are connected in parallel between the positive electrode and the negative electrode of the battery 21.

Here, since the IGBT series circuits 24U, 24V, and 24W have the same circuit configuration, the IGBT series circuit 24U will be described as an example.
The IGBT series circuit 24U includes an IGBT 31H constituting a positive arm, a diode 32H connected in parallel between the collector and emitter of the IGBT 31H, a capacitor 33H connected in parallel between the collector and emitter of the IGBT 31H, and a negative arm. , And a diode 32L connected in parallel between the collector and emitter of the IGBT 31L, and a capacitor 33L connected in parallel between the collector and emitter of the IGBT 31L.
Here, the gates of the IGBTs 31 </ b> H and 31 </ b> L are connected to the IGBT driver unit 25.

The IGBT driver unit 25 includes U-phase IGBT drive units 25UH and 25UL corresponding to the U-phase, V-phase IGBT drive units 25VH and 25VL corresponding to the V-phase, and W-phase IGBT drive units 25WH and 25WL corresponding to the W-phase. Then, under the control of the controller 23, the IGBTs 31H and 31L are driven in response to the inputted six motor drive control signals (load drive control signals) MDC.
The six systems of motor drive control signals MDC are motor drive PWM signals supplied from the primary side to the secondary side IGBT driver section 25 via an insulating unit IU such as a photocoupler.
The current sensors 27-U, 27-V, 27-W detect currents flowing through the corresponding phases, and output current detection signals SIU, SIV, SIW to the controller 23.
In the above configuration, the U-phase IGBT drive units 25UH and 25UL, the V-phase IGBT drive units 25VH and 25VL, the W-phase IGBT drive units 25WH and 25WL, and the corresponding IGBT correspond to the load circuit 13 for each system.

FIG. 3 is a schematic configuration block diagram of the controller.
The controller 23 is connected to a flyback transformer 11 that receives power from a power source 12 configured as a battery and performs power conversion, and a tertiary coil 50 that is a control coil of the flyback transformer 11. A diode 51 that rectifies the current flowing through the capacitor, a capacitor 52 that flows through the tertiary coil 50 and smoothes the rectified current, and a bleeder resistor RBLE that is connected in parallel to the capacitor 52 and has a variable resistance value. I have.
Here, the bleeder resistor RBLE is configured as, for example, a digital potentiometer, a voltage-controlled variable resistor, or the like in order to make the resistance value variable.

  The controller 23 also includes six motor drive control signals (U phase H, U phase) output to each IGBT from the IGBT driver unit 25 that drives the IGBT that constitutes the inverter circuit 24 for driving the three-phase AC motor 26. L, V-phase H, V-phase L, W-phase H, W-phase L), and load drive states for outputting load state detection signals SDET corresponding to the entire load state. Based on the detection circuit 41 and the load state detection signal SDET, an adjustment value that outputs a first adjustment value switching signal SOSC to an oscillator 43 described later and outputs a second adjustment value switching signal SFB to a feedback value adjustment circuit 53 described later A switching circuit, and an oscillator (triangular wave generation circuit) 43 that generates a predetermined triangular wave signal Vtri for PWM control based on the first adjustment value switching signal SOSC. To have.

  In this case, since the loads on the secondary side of the inverter circuit are a total of six IGBTs 31H and 31L and the IGBT driver unit 25 that drives them, six signals output from the IGBT driver unit 25 to each IGBT. It is possible to assume the amount of load driven by the presence or absence of each of (U-phase H, U-phase L, V-phase H, V-phase L, W-phase H, W-phase L). Since the decrease in the output voltage on the secondary side of the flyback transformer 11 can be predicted by the presence or absence of each of (U phase H, U phase L, V phase H, V phase L, W phase H, W phase L), If control (specifically feedback voltage control) is performed based on the load state detection signal SDET, control according to the load state can be performed.

  Further, until the drive of the three-phase AC motor 26 is stabilized, the control signal of each phase is not periodic, and six system signals (U phase H, U phase L, V phase) output to each IGBT. Since the H, V phase L, W phase H, and W phase L) themselves are not stable, the output voltage on the secondary side of the flyback transformer 11 is not stable. For this reason, in the present embodiment, the motor drive control signal of each phase (U phase H, U phase L, V phase H, V phase L, W phase H, W phase L) is not periodic. Alternatively, when the control value is fixed when driving is stopped, there is a phase that deviates greatly. Therefore, the switching frequency of the switching transistor 46 described later is shifted to a lower side, and the on-duty is not changed, and the switching transistor 46 is not changed. Of the rectifying diodes 48-1, 48-2,... Connected to the secondary coils 47-1, 47-2,. The influence of the forward voltage Vf of the diodes 48-1, 48-2,... Is suppressed to reduce the rate of change in the secondary output voltage due to load change.

  Further, the controller 23 divides the voltage of the bleeder resistor RBLE and outputs it as the original feedback voltage VFB0, and the feedback value adjustment for outputting the original feedback voltage VFB0 as it is or by amplifying the voltage and outputting it as the feedback voltage VFB. An error amplifier 54 that amplifies the difference between the circuit 53, the feedback voltage VFB, and the reference voltage VREF and outputs an error amplification signal Verr; a triangular wave signal Vtri output from the oscillator 43; and an error amplification signal output from the error amplifier 54 Verr, and a PWM control signal CPWM is output to the gate of the switching transistor 46 connected in series with the primary coil 45 of the flyback transformer 11 to perform a switching operation, Has .

Next, the operation of the embodiment will be described.
FIG. 4 is an operation flowchart of the embodiment.
In the initial state, the resistance value of the bleeder resistor RBLE and the frequency of the triangular wave signal Vtri output from the oscillator 43 are set to default values when the power supply device is started, and the feedback value adjustment circuit 53 receives the input original feedback voltage. The first adjustment value switching signal SOSC and the second adjustment value switching signal SFB are output so that VFB0 is directly output as the feedback voltage VFB.
When the power is turned on and the power supply device is activated (step S11), the controller 23 supplies the power supplied from the power supply 12 to the primary coil 45 of the flyback transformer 11, and converts the IGBT constituting the inverter circuit 24 into the IGBT 23. PWM signals (6 phase motor drive control signals (U-phase H, U-phase L, V-phase H, V-phase L, W-phase H, W-phase L)) output from the driving IGBT driver unit 25 to each IGBT. Load drive control signal) is output, and the three-phase AC motor 26 is driven (step S13). Here, as the PWM signal, a signal with a modulated pulse width is repeatedly input to drive each IGBT. In this embodiment, the presence or absence of a load drive control signal is detected as the presence or absence of a pulse of the PWM signal. ing.

In parallel with this, the power supplied to the primary coil 45 of the flyback transformer 11 is supplied to the tertiary coil 50, rectified by the diode 51, smoothed by the capacitor 52, and supplied to the bleeder resistor RBLE. The
As a result, the voltage of the bleeder resistor RBLE, that is, the voltage corresponding to the case where the load circuit 13-X of a predetermined one system is performing a steady operation, is supplied to the voltage dividing circuit 55. The voltage is divided according to the voltage dividing ratio of the resistors to be configured, and is output to the feedback value adjusting circuit 53 as the original feedback voltage VFB0 (step S14).
Thus, the feedback value adjustment circuit 53 outputs the input original feedback voltage VFB0 as it is to the error amplifier 54 as the feedback voltage VFB based on the second adjustment value switching signal SFB.

The error amplifier 54 amplifies the difference between the feedback voltage VFB and the reference voltage VREF and outputs an error amplification signal Verr to the non-inverting input terminal of the comparator 44.
In parallel with this, the oscillator 43 generates a predetermined triangular wave signal Vtri for PWM control based on the first adjustment value switching signal SOSC and outputs it to the inverting input terminal of the comparator 44.
The comparator 44 compares the triangular wave signal Vtri output from the oscillator 43 with the error amplification signal Verr output from the error amplifier 54, generates a PWM control signal CPWM, outputs it to the gate of the switching transistor 46, and performs switching. Let the action take place.
As a result, power of a predetermined voltage is supplied to the secondary coils 47-1 and 47-2 of the flyback transformer 11 and supplied to the load circuits 13-1, 13-2,.

When the output voltage Vout on the secondary side is stabilized based on the feedback voltage VFB and the driving of the three-phase AC motor 26 is stabilized, the load drive state detection circuit 41 is output from the IGBT driver unit 25 to each IGBT. Load circuits 13-1, 13-2,... Based on six systems of load drive control signals (U phase H, U phase L, V phase H, V phase L, W phase H, W phase L) That is, the number of load circuits that are driven simultaneously is detected, and the load state detection signal SDET corresponding to the detected load state fluctuation, that is, the output voltage value fluctuation amount corresponding to the load amount fluctuation is switched. It outputs to the circuit 42 (step S15).
Subsequently, the adjustment value switching circuit 42 outputs the first adjustment value switching signal SOSC to the oscillator 43 in accordance with the driving state based on the load state detection signal SDET, that is, the number of load circuits being driven simultaneously. The second adjustment value switching signal SFB is output to the feedback value adjustment circuit 53.

FIG. 5 is an explanatory diagram of the load state and the load driving process.
5A shows a state where none of the six IGBTs is driven (low load state), and FIG. 5B shows a state where some of the six IGBTs are driven (medium load state). FIG. 5C is an explanatory diagram of the load driving process corresponding to a state where all six systems are driven (high load state).
FIG. 6 is an explanatory diagram of the relationship between the load state of the power source and the output voltage.
As shown in FIG. 6, the power supply 12 has a characteristic that the output voltage decreases as the load increases, that is, in the case of this embodiment, the number of load circuits that are driven simultaneously increases. In the present embodiment, a region having relatively high linearity in the voltage range that can be output from the power supply 12 is used as the output voltage range.
In the present embodiment, since the load circuits 13-1, 13-2,... Have the same load amount during driving and can be assumed in advance, it is determined which load circuit is in a driving state. There is no need to identify, and if the number of load circuits in the driving state is known, the decrease in the output voltage on the secondary side can be grasped. Furthermore, even if the load circuit in the driving state is switched from the above situation, the current control can be continued if the number of load circuits in the driving state has not changed.

Hereinafter, the control according to the number of load circuits in the drive state will be specifically described.
In a state where none of the six IGBTs is driven (low load state) (step S16; no drive), the adjustment value switching circuit 42 outputs the second adjustment value switching signal SFB, and the output target voltage Vfb is As shown in FIG. 5A, the average value “Lave” in the output voltage range at low load is set and finally output from the feedback value adjustment circuit 53. At this time, the value of the bleeder resistance RBLE is also the value at low load. It is made to become.
In parallel with this, the adjustment value switching circuit 42 outputs a first adjustment value switching signal SOSC, and the oscillator 43 outputs a PWM control signal corresponding to the driving frequency at low load based on the first adjustment value switching signal SOSC. A predetermined triangular wave signal Vtri is generated and output to the comparator 44.

  As a result, the comparator 44 compares the triangular wave signal Vtri corresponding to the driving frequency oscf = H at the time of low load output from the oscillator 43 with the error amplification signal Verr output from the error amplifier 54, and performs low load driving. The PWM control signal CPWM corresponding to is generated and output to the gate of the switching transistor 46 to perform the switching operation, and the process proceeds to step S15 again.

  Also, in a state where a part of the six IGBTs is driven (medium load state) (step S16; partial drive), the second adjustment value switching signal SFB is output from the adjustment value switching circuit 42 and output. As shown in FIG. 5B, the target voltage Vfb is a predetermined function f having a load value (Load) as a parameter in the output voltage range at medium load (in the case of FIG. 5B, a linear function). The calculation value f (Load) can be approximated), and the voltage finally output from the feedback value adjustment circuit 53 is relatively high on the low load (for example, only one system operation) side in the medium load range. On the high load side (for example, 5 systems are operating) in the medium load range, the voltage finally output from the feedback value adjustment circuit 53 is set to a relatively low output voltage. The value of the leader resistor RBLE also to be a predetermined value at the time of medium load.

In parallel with this, the adjustment value switching circuit 42 outputs the first adjustment value switching signal SOSC, and the oscillator 43 outputs the PWM control signal corresponding to the driving frequency at the time of medium load based on the first adjustment value switching signal SOSC. A predetermined triangular wave signal Vtri is generated and output to the comparator 44.
Here, the driving frequency oscf at the time of medium load is set to a value lower than the driving frequency oscf = H at the time of low load, that is, the driving frequency oscf = L. This effectively lengthens the ON period of the switching transistor 46, and the conduction periods of the rectifying diodes 48-1, 48-2,... Connected to the secondary coils 47-1, 47-2,. This is because the influence of the forward voltage Vf of the diodes 48-1, 48-2,... Is suppressed to reduce the rate of fluctuation of the secondary output voltage due to load fluctuation.

  As a result, the comparator 44 compares the triangular wave signal Vtri corresponding to the driving frequency oscf = L at the time of middle load output from the oscillator 43 with the error amplification signal Verr output from the error amplifier 54, and performs low load driving. The PWM control signal CPWM corresponding to is generated and output to the gate of the switching transistor 46 to perform the switching operation, and the process proceeds to step S15 again.

Further, in a state where all six systems are driven (high load state) (step S16; full drive), the second adjustment value switching signal SFB is output from the adjustment value switching circuit 42, and the output target voltage Vfb is As shown in FIG. 5C, the average value Have in the output voltage range at the time of high load is set and finally output from the feedback value adjustment circuit 53. At that time, the value of the bleeder resistance RBLE is also the value at the time of high load. To be.
In parallel with this, the adjustment value switching circuit 42 outputs a first adjustment value switching signal SOSC, and the oscillator 43 outputs a PWM corresponding to the driving frequency oscf = H at the time of high load based on the first adjustment value switching signal SOSC. A predetermined triangular wave signal Vtri for control is generated and output to the comparator 44.

  As a result, the comparator 44 compares the triangular wave signal Vtri corresponding to the driving frequency oscf = H at the time of high load output from the oscillator 43 with the error amplification signal Verr output from the error amplifier 54, and performs low load driving. The PWM control signal CPWM corresponding to is generated and output to the gate of the switching transistor 46 to perform the switching operation, and the process proceeds to step S15 again.

  The above is a description of the control based on the number of load circuits in the driving state. However, as the actual control, when the number of load circuits in the driving state changes, according to the procedure described above, It is only necessary to shift to control corresponding to the number of load circuits. In other words, as long as the number of load circuits in the driving state has not changed, the current control can be continued even if the load circuits actually in the driving state have different combinations.

  Specifically, when it is detected that three motor drive control signals are output from six motor drive control signals MDC at any detection timing, it corresponds to three loads (medium load state). Control is performed. If it is detected at the next detection timing that five motor drive control signals have been output, a voltage drop (voltage fluctuation) of the output voltage Vout corresponding to the increased two systems occurs. Compensation is performed so that the output voltage Vout becomes constant. Further, at the next detection timing, when it is detected that two motor drive control signals are output, a voltage rise (voltage fluctuation) of the output voltage Vout corresponding to the reduced three systems occurs. Compensation is performed so that the output voltage Vout becomes constant. Furthermore, at the next detection timing, when it is detected that two motor drive control signals have been output again, it is possible to determine which load circuit is in the drive state without determining which load circuit is in the drive state. Since there is no change in the number, the control is continued as it is.

  As described above, according to the present embodiment, according to the load state (low load, medium load or high load), that is, according to the number of load circuits in the drive state, and consequently the number of load circuits. Since the frequency of the oscillator for generating the feedback waveform (including changing the resistance value of the bleeder resistor) and the PWM waveform supplied to the switching element is changed, an optimum output voltage corresponding to the load state can be obtained. At the same time, fluctuations in output voltage due to load fluctuations can be suppressed.

Therefore, the difference in output voltage between output systems can be reduced, and cross regulation can be improved. In a flyback type power supply device, it is easy to configure a circuit using a small flyback transformer.
In the above description, the feedback voltage adjustment by the feedback value adjustment circuit 53 and the change of the bleeder resistance RBLE are performed at the same time. However, only one of them can be used.

It is outline | summary structure explanatory drawing of this invention. It is a schematic block diagram of the motor drive device using the power supply device of embodiment. It is a general | schematic block diagram of a controller. It is an operation | movement flowchart of embodiment. It is explanatory drawing of a load state and a load drive process. It is a relation explanatory drawing of the load state of a power supply, and an output voltage.

DESCRIPTION OF SYMBOLS 10 Power supply device 11 Flyback transformer 12 Power supply 13-1, 13-2 Load circuit 14 Power conversion part 15 Drive state detection part 16 Adjustment value control part 20 Motor drive device 21 Battery 23 Controller 24 Inverter circuit 25 IGBT driver part (motor drive) circuit)
26 Three-phase AC motor 31H, 31L IGBT (motor drive circuit)
41 Load drive state detection circuit 42 Adjustment value switching circuit 43 Oscillator 44 Comparator 45 Primary coil 46 Switching transistor (switching element)
47 Secondary coil 53 Feedback value adjustment circuit 54 Error amplifier 55 Voltage divider circuit CPWM PWM control signal oscf Drive frequency MDC Motor drive control signal (load drive control signal)
RBLE bleeder resistance SDET load state detection signal SFB second adjustment value switching signal SOSC first adjustment value switching signal VFB feedback voltage VREF reference voltage Verr error amplification signal Vfb output target voltage Vin input voltage Vout output voltage Vtri triangular wave signal

Claims (3)

A multi-output type flyback transformer having a control coil and a bleeder resistor connected to the control coil; a load connected to each of a plurality of outputs of the flyback transformer; The output voltage of the back transformer is supplied, and the input voltage on the primary side of the flyback transformer is controlled based on the feedback voltage value that changes according to the voltage of the bleeder resistor, and the output voltage value is adjusted to a constant value. In a power supply device equipped with an adjustment circuit,
Each of the plurality of loads is driven by repeatedly inputting a load drive control signal, and each of the loads has the same load amount during driving,
Based on the presence or absence of the load drive control signal, input to the adjustment circuit to detect a change in the number of loads being driven and to compensate for a change in the output voltage due to the change in the number of loads A power supply apparatus comprising a feedback value adjustment circuit for adjusting the feedback voltage value. The power supply device according to claim 1, wherein
The load is a motor drive circuit corresponding to any phase of a synchronous multiphase motor, and the load drive control signal is supplied from the primary side to the secondary side via an insulation circuit, and each motor drive circuit Is a PWM control signal in the corresponding phase,
The feedback value adjusting circuit detects the PWM control signal on the primary side. The power supply device according to claim 1 or 2,
A power conversion switching element connected to the primary coil of the flyback transformer;
A low load state in which the number of driven loads is the smallest, a high load state in which the number of driven loads is the largest, and an intermediate load state between them,
In the medium load state, the switching element is driven at a predetermined switching frequency lower than a predetermined switching frequency of the switching element in the low load state and the high load state.

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