JP4185110B2 - Automotive power converter - Google Patents

Description

  The present invention relates to a power conversion device mounted on an automobile or the like, and in particular, a detection value of a DC voltage of a power converter is transmitted to a control calculation portion of the power conversion device via an electrically insulated communication element. The present invention relates to an in-vehicle power converter.

  Conventionally, as an in-vehicle power converter mounted on a vehicle, a power converter that performs power conversion between a DC power source and a load such as an AC motor is provided, and the DC voltage value of the power converter is electrically insulated. Therefore, once the DC voltage detection signal is converted into digital data in the power converter, it is processed into communication data and transmitted to the control unit using a serial communication method such as start-stop synchronization. After that, there is again one in which the data for communication is processed into the DC voltage value used for the control calculation in the control unit. (For example, see Patent Document 1)

Japanese Unexamined Patent Publication No. 2005-33997 (paragraph 0008, paragraph 0009, FIG. 1, FIG. 2)

  Such a conventional in-vehicle power conversion device needs to include a microcontroller having an A / D converter, a serial communication device, and an arithmetic processor in the power converter for sending out DC section voltage information. This increases the cost of parts and the volume of the apparatus, which is not desirable. In addition, when mounting a function different from the transmission of the DC part voltage information in order to balance the increase in the component cost, the processing density is increased and the sending process cycle of the DC part voltage information is extended. The elapsed time required for transmission of DC section voltage information may be inappropriate.

  For this reason, if a microcontroller with a high oscillation frequency of the clock oscillator is selected to increase the processing capacity of the microcontroller, the operation can be stabilized due to a mismatch with the device temperature due to a further increase in component costs and a rise in temperature due to self-heating. This leads to disadvantages such as a decline in sex.

  In addition, in the conventional apparatus, since encoded binary representation data is transmitted by serial communication, the logical value information to be transmitted has different importance for each bit. For example, the logical value information of the sixth digit from the lower order of the binary number representation data has a weight of 2 to the (6-1) th power as the value, and the logical value information of the second digit from the lower order has a value of (2- 1) It has a power of power, and for the DC voltage data after decoding, the higher-order logical value information has a larger influence on the numerical value.

  Therefore, if the logic of the transmission signal is wrong due to the effect of noise superimposed on the transmission path, the DC voltage value after decoding becomes very inaccurate depending on the timing at which the noise is superimposed. In order to prevent this, even if data transfer detection bits such as a parity bit are added and serial communication is performed, it only detects that data transfer has occurred in the DC voltage value of the cycle, and The amount of error in the DC part voltage value due to falling is unknown, and the DC part voltage information cannot be updated in this period.

  The present invention has been made in order to solve the above-described problems of the conventional device, and is a control unit that can control voltage information and the like of the DC section in an electrically insulated state with a simple configuration and low cost. It aims at providing the vehicle-mounted power converter device which can be transmitted to.

An in-vehicle power converter according to the present invention includes a power converter that is provided between a DC power supply and an electric load and performs power conversion between the DC power supply and the electric load by switching of the power element; An in-vehicle power conversion device including a control unit that controls switching, wherein the power converter includes a voltage detector that detects a voltage of the DC unit, and a voltage of the DC unit that is detected by the voltage detector. DC part voltage input interface that outputs a standardized DC part voltage by standardizing with a preset maximum value of voltage change range, and voltage modulation by delta-sigma modulation of the standardized DC part voltage every predetermined period A delta-sigma modulator as a signal, and an insulating communication element that electrically insulates the voltage modulation signal and transmits the signal to the control unit, the control unit including the transmission A signal input interface for inputting the voltage modulated signal, a demodulating means for demodulating the voltage value of the DC section by counting the logic state of the voltage modulated signal within the predetermined period, and a signal demodulated by the demodulating means And a switching signal generation unit that generates a switching control signal for controlling the switching of the power element.

  According to the on-vehicle power converter according to the present invention, the voltage information and the like of the direct current portion of the power converter can be transmitted to the control unit in an electrically insulated state with a simple configuration and low cost. A power converter device can be obtained.

First, the technology that forms the basis of the present invention will be described with reference to the drawings.
1. Technology underlying the invention
FIG. 8 is a block diagram showing an overall system configuration including an in-vehicle power conversion device according to the technology underlying the present invention. In FIG. 8, in order to control the AC motor 3 which is a power source of the automobile, the DC power from the DC power source 2 such as a battery is converted into AC power by using the three-phase inverter 6 constituting the power converter 4. And supplied to the AC motor 3.

  Here, in order to control the AC motor 3 to a desired state, the control calculation unit 24 in the control unit 5 causes the motor current flowing in the armature winding of the flow motor 3, the rotation angle of the rotor of the AC motor 3, Based on information such as the DC voltage of the three-phase inverter 6, a motor control calculation such as a well-known vector control method is performed, and an AC voltage command amount to be applied to the terminal of the AC motor 3 (hereinafter referred to as an AC voltage command). Is calculated. The DC voltage of the three-phase inverter 6 is detected by the voltage detector 10, and the motor current is detected by the current detectors 14a, 14b, and 14c. The rotation angle of the rotor is calculated based on the rotation signal output from the rotation detector 15.

  The AC voltage command is subjected to pulse width modulation (hereinafter referred to as PWM) by the switching signal generation unit 25, and has a rectangular wave shape for switching the transistors 7a to 7f constituting the power elements in the power converter 4. Converted to a switching signal. The transistors 7 a to 7 f are switched by this switching signal, so that a voltage which is microscopically distributed in a rectangular wave shape or macroscopically in a sine wave shape is applied to the terminal of the AC motor 3.

  In the control unit 5, signals such as an AC motor operation command, motor current, rotation, and DC voltage are received via the signal input interface 20, and can be used for arithmetic calculation by the A / D converter 21 and the serial communication device 22. Processed into digital data. Further, the rotation angle and speed are calculated by the rotation angle / speed calculation means 23 of the rotor based on the rotation signal, the motor calculation calculation is further performed by the control calculation unit 24, and the AC voltage applied to the AC motor 3 is calculated. Calculate the command amount.

  At this time, transmission of the switching signal from the control unit 5 to the power converter 4 requires electrical insulation using the insulated communication element 13 such as a photocoupler. That is, in the in-vehicle power conversion device particularly when the AC motor 3 is used as a power source for driving the vehicle, in order to supply the AC motor 3 with electric power of about several [Kw] to several tens [Kw]. The voltage range of the DC power supply 2 is about 40 [V] to several hundred [V], while the control unit 5 is constituted by an electronic circuit that operates in a voltage range of tens [V] or less. If the control unit 5 is not electrically insulated from the power converter 4 connected to the control unit 5, the control unit 5 may be damaged by overvoltage.

  For the same reason, the motor current, the rotation angle and rotation speed of the rotor, and the DC voltage signal must be input to the control unit 5 while being insulated from the DC power supply 2. In particular, the DC voltage is a signal detected by the voltage detector 10 that is directly connected to the DC power supply 2, and insulation must be fully considered. However, while satisfying the high-accuracy characteristics and immediate transmission characteristics required for the motor control calculation, the DC section voltage information is electrically isolated from the power converter 4 and transmitted to the control unit 5 in an analog amount for a continuous time. It becomes difficult to do.

  A transformer, a photocoupler, or the like can be used as the insulating communication element 13, but in the case of a transformer, the signal that can be transmitted is an alternating current, and the DC section voltage information with a small amount of change in temporal amplitude is highly accurate. Cannot be transmitted. In the case of a photocoupler, since the amplitude ratio of the input signal and the output signal is not constant and there is no linearity, DC part voltage information cannot be transmitted with high accuracy as well.

  For this reason, the detection of the DC voltage by the voltage detector 10 and the transmission of information to the control unit 5 are performed by sampling the signal of the insulating communication element 13 in discrete time and converting it into a digital signal whose magnitude is quantized. To be done. FIG. 9 is a block diagram illustrating a processing path for transmitting information on the DC voltage detected by the voltage detector 10 in the power converter 4 to the control unit 5 while being electrically insulated. First, the DC voltage signal from the voltage detector 10 is input to the signal input interface 11 and converted by the subsequent microcontroller 12 into a signal within a handleable range using a multiplication, addition, subtraction circuit, or the like. Is done.

  The microcontroller 12 includes an A / D converter 31 that converts an analog value into a digital value used for arithmetic calculation, an arithmetic processor 32 that sequentially executes arithmetic calculation by software, and a digital value between the outside of the microcontroller 12. A serial communication device 33 for serial communication is included. The DC voltage signal input to the microcontroller 12 is sampled and quantized by the A / D converter 31 and converted into a digital value.

  The signal converted into the digital value is subsequently input to the arithmetic processor 32 and further transferred to the serial communication device 33. The serial communication device 33 converts the digital value of the DC voltage signal into a binary-represented digital value using an asynchronous serial communication method realized by a semiconductor communication device such as UART (Universal Asynchronous ReceiVer and Transmitter). Each digit (represented by binary values of “1” and “0”) is output in time series at predetermined time intervals. These operations in the microcontroller 12 are executed based on the clock signal from the clock oscillator 34.

  Next, the serial communication signal output from the serial communication device 33 is electrically insulated via the insulation communication element 13 and transmitted to the control unit 5, and the voltage level corresponding to the binary logic by the signal input interface 20. After waveform shaping to recover the rise and fall characteristics degradation of the signal, it is input to the microcontroller 26. The microcontroller 26 includes a serial communication device 22, a clock oscillator 28, and an arithmetic processor 27. The arithmetic processor 27 includes an A / D converter 21, a rotation angle / speed calculator 23, and a control calculator 24 shown in FIG. 8.

  The serial communication signal whose waveform has been shaped by the signal input interface 20 is received by the serial communication device 22 and transferred to the arithmetic processor 27. The arithmetic processor 27 decodes the received data as a DC section voltage value and uses it for arithmetic calculation of motor control as the control arithmetic section 24. These operations in the microcontroller 26 are executed based on a clock signal from the clock oscillator 28.

  At this time, after the signal transmission from the detection of the DC section voltage to the control unit 5, the procedure and processing load until the DC section voltage value, which is digital data usable by the arithmetic processor 27, is classified as follows. The FIG. 10 is a list showing this procedure. First, when the A / D converter 31 for A / D converting the DC part voltage signal is activated by the “A / D converter activation instruction” of the procedure 1, a predetermined preparation time is required, and then the operation is possible. It becomes. Next, the sampling of the DC part voltage (sampling) and the holding of the value (holding) are performed by “sample, hold” in procedure 2, and further, the held DC part by “A / D conversion” in procedure 3 The voltage holding value is quantized, that is, converted into a digital value.

  When the A / D conversion by the procedure 3 is completed, the processor 32 is notified that the A / D conversion result can be read due to the “program execution delay” of the procedure 4, and the processor 32 receives the notification. The process that is currently being executed is temporarily suspended and the process is switched so that the conversion result reading process can be performed. Subsequently, the A / D conversion result is read and processed into a data state in which serial transmission to the control unit 5 is possible by the procedure 5 “Conversion result reading and digitization”. Next, according to “Serial communication device activation, data set” of procedure 6, the serial communication device 33 is activated and the data for transmission is set.

  The DC part voltage value transmission data set in the serial communication device 33 is a data representation of the binary number in the data representation of the binary number according to the procedure 7, such as a communication control bit such as a start bit and a stop bit, a parity bit, etc. Bits for detecting data shift are added and transmitted as time-series data in which the voltage level of the signal line is changed corresponding to the logical value of each digit (bit) at every predetermined interval. The change in the voltage level of the signal line is transmitted to the serial communication device 22 of the control unit 5 via the insulating communication element 13 and the signal input interface 20, and is formed as reception data.

  When the reception of the serial communication data is completed and the reception data is formed, the arithmetic processing unit 27 is notified that the reception data can be read. Due to the “delay”, the current processing is temporarily interrupted, and the processing is switched so that the received data reading processing can be performed. Furthermore, according to procedure 9 “Read serial communication received data, confirm reception error”, when the received data is read, whether or not a reception error has occurred is confirmed. If no reception error has occurred, the read data is processed and DC Decoded as a partial voltage value.

  In the in-vehicle power converter according to the technology 1 that is the basis of the present invention, it is assumed that power control is performed by controlling the output torque of the AC motor 3. At this time, the elapsed time from when the voltage detector 10 detects information on the DC section voltage used for the control calculation of the AC motor 3 until it is reflected in the motor control calculation in the control calculation section 24 corresponds to a dead time. This affects the phase characteristics of the frequency transfer characteristics of the control system. Here, the phase delay at the upper limit frequency in the pass band of the control system is small or large at 180 ° as a boundary, or how close to 180 ° when the phase delay is small, whether the control system is stable or not and which response There is a correlation with the degree of vibration.

  For this reason, it is desirable that the phase delay at the upper limit frequency in the passband of the control system is small, which indicates that it is better that the elapsed time required for transmission of the DC part voltage information is short. In the output torque control of the AC motor 3, the upper limit frequency of the pass band of the control system is set to 318.3 [Hz] (2000 [rad / s]) according to the request of the follow-up speed (speed response) of the actual output torque with respect to the target output torque. When set, when the elapsed time required for transmission of DC section voltage information is 1 [ms], the phase delay is 0.001 × 318.3 × 360 ° = 14.6 °, which is an upper limit guideline for the phase delay. There is only 65.4 ° margin for 180 °. If the sum of the phase delay (response delay) of the AC motor 3 as the control target and the phase delay of the control calculation exceeds 65.4 °, the control system becomes unstable.

  On the other hand, when the elapsed time required for transmission is as short as 100 [us], the phase delay is 0.0001 × 318.3 × 360 ° = 11.5 °, which is 168.5 ° with respect to 180 °. Have a margin. Thus, the elapsed time required for transmission of the DC section voltage information is a factor that greatly affects the control performance, and it is desirable that the time is shorter.

1. Technology underlying the invention
FIG. 11 shows a configuration diagram of the entire system including another in-vehicle power conversion device that is the basis of the present invention. This in-vehicle power conversion device includes a DC-DC converter 36 that converts an input voltage from a DC power source 2 such as a battery into a desired target output voltage and supplies it to an electric load. The DC-DC converter 36 constituting the power converter 4 includes an input filter capacitor 37, a reactor 38, a power element in which transistors 39a and 39b and flywheel diodes 40a and 40b are connected in antiparallel, and a smoothing capacitor 9, and the transistor The output voltage applied to the terminal of the electric load 35 is controlled by adjusting the storage and release of the energy of the reactor 38 by switching 39a and 39b.

  Here, in order to control the output voltage of the DC-DC converter 36 so as to coincide with a desired target output voltage, the control arithmetic unit 24 in the control unit 5 outputs the DC voltage on the output side of the DC-DC converter 36, that is, The voltage between the terminals of the smoothing capacitor 9 is fed back and matched with the target output voltage to perform an output voltage control calculation to calculate the switching duty ratio of the transistors 39a and 39b. Next, based on the calculated duty ratio, the switching signal generator 25 generates a switching signal to drive the transistors 39a and 39b.

  In the case of the in-vehicle power conversion device shown in FIG. 11, the control unit 5 is configured by an electronic circuit that operates in a voltage range of tens [V] or less, like the in-vehicle power conversion device used for motor control shown in FIG. Therefore, if the power converter 4 connected to the DC power source 2 is not electrically insulated, the power converter 4 is damaged due to overvoltage. Therefore, it is necessary to electrically insulate and transmit the output side direct current voltage information of the DC-DC converter 36 to the control unit 5, and in the same manner as in the case of the power conversion device used for motor control shown in FIG. The transmission of the output side DC section voltage information is realized by serial communication in the procedure shown in FIG. 10 using the microcontroller 12 in the power converter 4 based on the processing path shown in FIG.

  Also in the case of an in-vehicle power converter including a DC-DC converter configured as described above, when performing voltage conversion by performing control so that the output voltage follows and matches a desired target output voltage, the DC-DC converter The elapsed time from when the information on the output side DC section voltage is detected by the voltage detector 10 until it is reflected in the output voltage control calculation in the control calculation section 24 is equivalent to a dead time and passes through the output voltage control system. Unless the time is relatively short with respect to the upper limit frequency, the output voltage control characteristics deteriorate and sufficient performance cannot be obtained.

Embodiment 1 FIG.
1 is a configuration diagram of the entire system including an in-vehicle power converter according to Embodiment 1 of the present invention. In FIG. 1, the same or corresponding parts as those shown in FIG. Show. In FIG. 1, direct current power of a direct current power source 2 such as a battery is converted into alternating current power by an in-vehicle power conversion device 1 and supplied to an alternating current motor 3 serving as a power source of an automobile.

  The in-vehicle power converter 1 includes a power converter 4, a control unit 5, and motor current detectors 14 a, 14 b, and 14 c that detect a motor current flowing through the AC motor 3. The power converter 4 includes a three-phase inverter 6, a voltage detector 10 that detects the DC voltage of the power converter 4, a DC voltage input interface 11 that normalizes the DC voltage with the maximum value of the change range, A delta sigma modulator 45 that delta-sigma modulates the standardized DC voltage and outputs a DC voltage modulated signal, and an insulated communication element 13 that electrically insulates the DC voltage modulated signal and transmits it to the control unit 5 And.

  The three-phase inverter 6 includes transistors 7a to 7f, flywheel diodes 8a to 8f, and a smoothing capacitor 9. The emitter of the transistor 7a is connected to the collector of the transistor 7b, and the flywheel diode 8a has an anode connected to the emitter of the transistor 7a and a cathode connected to the collector of the transistor 7a so as to be in antiparallel with the transistor 7a.

  The flywheel diode 8b has an anode connected to the emitter of the transistor 7b and a cathode connected to the collector of the transistor 7b so as to be in antiparallel with the transistor 7b. The transistors 7a and 7b and the flywheel diodes 8a and 8b A phase arm is constructed. The transistors 7a and 7b and the flywheel diodes 8a and 8b have similar connection relations so that the transistors 7c and 7d and the flywheel diodes 8c and 8d have a V-phase arm, and the transistors 7e and 7f and the flywheel diodes 8e and 8f have a W-phase. An arm is configured.

One end of the smoothing capacitor 9 is connected to the high potential side terminal P ₀ of the output of the DC power source 2 together with the collectors of the transistors 7 a, 7 c, 7 e which are the upper ends in the respective phase arm diagrams. end is a lower end in view of each phase arm transistors 7b, 7d, is connected to the low potential side terminal N ₀ of the output of the DC power source 2 to supply the emitter of 7f.

Further, the U-phase terminal of the AC motor 3 is connected to a connection portion between the emitter of the transistor 7a and the collector of the transistor 7b, which is an intermediate point of the U-phase arm. Similarly, the V-phase terminal of the AC motor 3 is connected to the emitter of the transistor 7e, which is the middle point of the W-phase arm, and the transistor 7f, at the connection portion between the emitter of the transistor 7c, which is the middle point of the V-phase arm, and the collector of the transistor 7d. The W-phase terminal of the AC motor 3 is connected to the collector connection part.
Therefore, the terminal voltage of AC electric motor 3 can be adjusted by switching transistors 7a to 7f to switch between conduction and non-conduction.

  The control unit 5 includes a signal input interface 20, an A / D converter 21, a serial communication device 22, a rotation angle / speed calculation unit 23, a control calculation unit 24, a switching signal generation unit 25, and a demodulation unit 46. It has. The control unit 5 receives signals such as the operation command of the AC motor 3, the motor current, the rotation angle of the rotor of the AC motor 3, the rotation speed, and the DC voltage, and performs motor control calculation based on these information, A switching signal for operating each of the transistors 7 a to 7 f of the inverter 6 is generated and transmitted to the three-phase inverter 6.

  In the on-vehicle power converter configured as described above, the information on the DC voltage in the power converter 4 is electrically insulated and transmitted to the control unit 5 by the configuration and path described below. FIG. 2 is a block diagram showing a detailed configuration and path of DC part voltage information transmission, and DC part voltage information transmission will be described with reference to FIG. First, the voltage detector 10 detects the DC part voltage of the power converter 4 and outputs a DC part voltage signal. This signal is input to the DC part voltage input interface 11 and becomes a standardized DC part voltage signal having a value range of 0.0 to 1.0 normalized by a maximum value of a preset voltage change range. Normalization is performed by passing the DC voltage signal through the amplifier circuit in the DC voltage input interface 11.

  When the standardized DC part voltage signal is input, the delta sigma modulator 45 modulates it to form a DC part voltage modulated signal. Here, the delta-sigma modulator 45 includes a sampler 51, a subtractor 52, an adder 53, delay units 54 and 56, a 1-bit quantizer 55, a 1-bit D / A converter 57, and an amplification. The circuit 58 includes a clock oscillator 59 and a frequency divider 60. The delta sigma modulator 45 operates as follows.

  First, the standardized DC voltage signal input to the delta sigma modulator 45 is sampled by the sampler 51 with a sampling period Δtm. This sampling period Δtm corresponds to the update unit time of the DC unit voltage value in the motor control calculation in the control calculation unit 24 of the control unit 5, and is compared with the reciprocal (= cycle) of the control passband upper limit frequency of the motor control. In addition to reducing the phase delay due to the elapsed time of DC part voltage information transmission, macroscopically, the change in voltage value can be regarded as continuous.

  Next, the subtractor 52 delays the output of the 1-bit D / A converter 57 from the standardized DC voltage signal after sampling, that is, the output of the 1-bit quantizer 55 by one clock and converts it into an analog quantity. Is transmitted to the adder 53. Subsequently, the adder 53 adds the output of the subtractor 52 and the output of the delay unit 54 and outputs the result. Here, the adder 53 and the delay unit 54 constitute a discrete-time integrator that adds the input value of the current cycle to the integration result of the previous clock cycle.

  Further, the output of the adder 53 is compared with the threshold value 0.0 by the 1-bit quantizer 55, and when the value is 0.0 or more (sign is positive), the logical value “1” is 0.0. When the value is less than (the sign is minus), the logical value “−1” is output. The output of the 1-bit quantizer 55 passes through the delay unit 56 and 1-bit D / A converter 57 as described above and is fed back to the subtractor 52.

  The above operation from the input of the sampler 51 to the output of the 1-bit quantizer 55 compares the sampled input signal with the 1-bit quantized output logic of the previous clock cycle, and the difference (quantization error). ), That is, by integrating with negative feedback, a signal whose pulse density is modulated by binary logic so that the quantization error approaches zero on average is output.

  At this time, the delay units 54 and 56 perform delay processing with the period Δte as a unit of one clock based on the clock signal output from the clock oscillator 59. Further, the sampler 51 samples the period Δtm obtained by dividing the clock signal from the clock oscillator 59 by the frequency divider 60 as a sampling period. That is, as described above, the sampling period Δtm is set to a period of about 1/10 or more of the reciprocal (= period) of the control passband upper limit frequency of the motor control, and an integral multiple of the period Δte is the sampling period. A clock signal is generated so as to be Δtm.

  Next, the amplifying circuit 58 adds a logical value “1” as an offset amount to the output of the 1-bit quantizer 55, and then doubles the result to obtain a binary value of “1” and “0”. After converting the change width so as to change, the voltage level “H” is set to correspond to the logical value “1”, and the voltage level “L” is set to correspond to the logical value “0” to set the DC part voltage. No modulation signal is output from the delta-sigma modulator 45. Further, the DC voltage modulation signal is electrically insulated by an insulated communication element 13 such as a photocoupler or a transformer and transmitted to the control unit 5.

  Subsequently, the signal input interface 20 in the control unit 5 inputs the DC voltage modulation signal, doubles the amplitude, subtracts the voltage level corresponding to the logical value “1”, and outputs the result to the demodulator 46. With this process, the DC voltage modulation signal is set to a voltage level corresponding to the logical values “1” and “−1”.

  Next, the demodulator 46 demodulates the DC voltage value based on the DC voltage modulation signal that has passed through the signal input interface 20. Here, the demodulating means 46 includes samplers 61 and 64, an adder 62, delay units 63 and 68, an amplifier circuit 65, a clock oscillator 66, and a frequency divider 67, and its detailed operation. Is as follows.

  First, the sampler 61 samples the output signal of the signal input interface 20 at the sampling period Δte, and outputs a logical value (either “1” or “−1”) corresponding to the voltage level to the adder 62. Next, the adder 62 adds the logical value from the sampler 61 and the output of the delay unit 63 and outputs the result. The delay unit 63 delays and transmits the output of the adder 62 by one clock, and the adder 62 and the delay unit 63 add the input logic value of the current cycle to the result of the previous cycle. 69 is constituted.

  Further, the logic state count result output from the adder 62 is sampled by the sampler 64 at the sampling period Δtm, transmitted to the amplifier circuit 65, and then multiplied by Δte / Δtm to become the DC voltage value. That is, the logic of the DC voltage modulation signal is counted over the sampling period Δtm corresponding to the update unit time of the DC voltage information, the distribution states of the logical values “1” and “−1” are grouped for each Δtm, The voltage will be reproduced (demodulated). This DC unit voltage value is transmitted to the control calculation unit 24 and used as input information for the motor control calculation. The DC voltage value demodulated here is after normalization, and the value range is 0.0 to 1.0. In order to obtain the DC voltage value as a physical quantity, the maximum value of the voltage change range is further multiplied.

  Here, the sampler 61 and the delay units 63 and 68 operate based on the clock signal output from the clock oscillator 66 with the same period Δte as that of the delta sigma modulator 45 as a unit of one clock. The sampler 64 samples the output of the logic state counter 69 with a period Δtm obtained by dividing the clock signal from the clock oscillator 66 by the frequency divider 67 as a sampling period.

  On the other hand, the logic state counter 69 clears the count value to zero every period Δtm based on a signal obtained by delaying the output of the frequency divider 67 by 1 clock Δte by the delay unit 68. That is, the logic state counter 69 counts the logic state in each cycle with the period Δtm as a time range, clears the count value to zero after one clock Δte of the timing when the sampler 64 has sampled, and again Operate to begin counting logic states.

  The operation waveforms of the modulation and demodulation of the DC section voltage information described above are shown in FIG. In FIG. 3, (a) shows the DC part voltage value after demodulation corresponding to the DC part voltage signal before modulation, and (b) shows the logic state count value in the demodulating means 46 and the DC part voltage after demodulation. Each value is shown, and in each case, the horizontal axis is a time axis having a common scale.

  A characteristic line Vc1 in FIG. 3A is a standardized DC voltage output from the signal input interface 11, and is a signal that changes in continuous time. A characteristic line Vd1 is a post-sampled standardized DC voltage obtained by sampling the characteristic line Vc1 with the sampler 51 in the delta-sigma modulator 45 at a period Δtm, and is a signal that changes stepwise in discrete time. Further, the characteristic line Vm1 is a demodulation result of the DC voltage value output from the demodulating means 46.

  In FIG. 3, the standardized DC section voltage sampled at time Ta is demodulated as a DC section voltage value at time Ta 'after a period Δtm. Also, the normalized DC section voltage sampled at time Tb is the DC section voltage at time Tb ′ after the period Δtm, and the normalized DC section voltage sampled at time Tc is the DC section voltage at time Tc ′ after the period Δtm. Demodulated as a value. Here, time Ta 'coincides with time Tb, and time Tb' coincides with time Tc. Since the normalization processing at the signal input interface 11 is performed at a much higher speed and with less time delay than the modulation processing at the delta-sigma modulator 45 and the demodulation processing at the demodulation means 46, the voltage detector 10 Is detected (demodulated) as a DC voltage value from the demodulator 46 after a period Δtm.

  Also, a characteristic line CNT1 shown in FIG. 3 (b) is obtained by multiplying the logical state counting result of the DC part voltage modulation signal output from the logical state counter 69 by Δte / Δtm, and is displayed every period Δtm. It is cleared to zero and becomes a sawtooth waveform. The characteristic line Vm1 is the same as that shown in FIG. 3A, and the sampler 64 samples and amplifies at the times Ta ′, Tb ′, Tc ′,... Corresponding to the top of the sawtooth waveform of the logic state count value. This is a result of demodulating the DC voltage value multiplied by Δte / Δtm by the circuit 65.

  4A and 4B are operation waveforms for modulation and demodulation of DC part voltage information with the time extended to Δtm of the DC part voltage information update period. FIG. 4A shows a DC part voltage signal before modulation, and FIG. 4B shows a delta sigma. The output of the integration operation part of the modulator 45 (the output of the adder 53), (c) the DC part voltage modulation signal, (d) the logic state count value in the demodulating means 46 and the DC part voltage after demodulation. Each value is shown, and in each case, the horizontal axis is a time axis having a common scale.

  In FIG. 4A, the characteristic line Vc2 is a standardized DC voltage output from the signal input interface 11, and the characteristic line Vd2 is a sample of the characteristic line Vc2 by the sampler 51 in the delta-sigma modulator 45 at a period Δtm. It is the normalized DC part voltage after sampling. The sampler 51 samples Vc2 at time Td and then samples it at time Te after Δtm, and holds the value sampled at time Td from time Td to time Te.

  In FIG. 4B, the characteristic line Itg2 is an output of the integration operation portion of the delta-sigma modulator 45, and in FIG. 4C, the characteristic line Msig2 is a DC voltage modulation signal, and the characteristic line Itg2 Is passed through a 1-bit quantizer 55 and the result of comparing with a threshold value 0.0 is expressed by binary logic “1” and “−1”, and then passed through an amplifying circuit 58 to a voltage level “H” and a voltage level. The signal transmission is “L”. In FIG. 4, when itg2 is less than the threshold value 0.0 and a negative value, the DC voltage modulation signal is a voltage level "L", and when Itg2 is a threshold value 0.0 or more and a positive value, the DC voltage modulation is performed. The signal is at voltage level [L].

  Here, in the integration operation and 1-bit quantization operation, one clock cycle Δte is used as a processing unit time, and the clock signal is generated so that an integer multiple of Δte becomes Δtm. The voltage modulation signal is sequentially transmitted as a pulse train with the period Δtm as the development and transmission period of the voltage information. The ratio of Δtm and Δte at this time corresponds to the resolution of the modulation information, and the smaller Δte is relative to Δtm, the smaller the error generated in the DC voltage value after demodulation due to modulation and demodulation.

  The characteristic line CNT2 in FIG. 4D is a display obtained by multiplying the logical state count value of the DC voltage modulation signal output from the logical state counter 69 by Δte / Δtm, and the characteristic line Vm2 is the demodulated direct current. Part voltage value. In FIG. 4, the logic state count value at time Td is sampled, and the DC part voltage value of the demodulation result is also determined. Further, after Δte of the processing unit time, the logical state count value is once cleared to zero, and the logical state count starts again from zero. Here, the sampler 61 in the demodulating means 46 outputs a logical value “1” when the DC voltage modulation signal is at the voltage level “H”, and outputs a logical value “−1” when the voltage level is “L”. Therefore, each count is performed by adding “1” and subtracting “1” (adding “−1”).

  When Δtm elapses from time Td and time Te is reached, the logic state count value is sampled again, multiplied by Δte / Δtm, and the DC voltage value of the demodulation result is determined. Here, the standardized DC voltage sampled at time Td is converted into a modulated signal for Δtm, transmitted, and demodulated at time Te. In other words, information is transmitted in a state that can be used for control calculation with an elapsed time of Δtm.

  With the configuration and operation described above, the DC voltage information of the power converter 4 is electrically insulated and transmitted, and is ready for arithmetic calculation in the control calculation unit 24 in the control unit 5.

  Next, motor control calculation and generation of a switching signal for operating the transistor 7 will be described with reference to the drawings. FIG. 5 is a block diagram for explaining the flow of control calculation signals in the control unit 5. In FIG. 5, first, a DC voltage modulation signal, a motor operation command signal, a motor current signal, and a rotation signal are input from the outside of the control unit 5 and transmitted to the signal input interface 20.

  The signal input interface 20 performs conversion to a desired voltage level, waveform shaping for recovering deterioration of the signal rise and fall characteristics, etc., corresponding to each input signal, and then demodulates the DC voltage modulation signal. The motor operation command signal is transmitted to the serial communication device 22, the motor current signal is transmitted to the A / D converter 21, and the rotation signal is transmitted to the rotation angle / speed calculation device 23.

  The demodulating means 46 demodulates and outputs the DC voltage value as described above. The serial communicator 22 receives an operation command signal of the AC motor 3 input by serial communication from an external device of the in-vehicle power converter 1 (not shown), and outputs received data. The A / D converter 21 samples and quantizes the three-phase motor current of the AC motor 3 detected by the motor current detectors 14a, 14b, and 14c, converts the current into a digital value, and outputs the digital value. The rotation angle / speed calculation means 23 calculates and outputs the rotation angle and rotation speed based on the rotation signal output from the rotation detector 15.

  Further, the control calculation unit 24 performs a motor control calculation based on the vector control method and calculates a command amount of the AC voltage applied to the AC motor 3. Here, the control calculation unit 24 includes a current command generation unit 72, subtracters 73 and 74, a d-axis current controller 75, a q-axis current controller 76, a first coordinate converter 71, and a second coordinate. The detailed operation is as follows.

  First, the current command generator 72 receives the DC voltage value from the demodulator 46, the received data of the motor operation command signal from the serial communication device 22, and the rotation speed from the rotation angle / speed calculator 23. The received data of the motor operation command signal is decoded as an output torque command of the AC motor 3, and determines the operating point of the AC motor 3 together with the rotation speed. Moreover, the voltage (line voltage) between the terminals of the AC motor 3 that can be output by the three-phase inverter 6 is calculated from the DC voltage value, and based on these, the target current amount in the direction matching the rotor magnetic flux of the AC motor 3 is calculated. (D-axis current command value) and a target current amount (q-axis current command value) in a direction orthogonal to the rotor magnetic flux are calculated.

  Next, the first coordinate converter 71 converts the three-phase motor current value into the AC motor 3 based on the three-phase motor current value from the A / D converter 21 and the rotation angle from the rotation angle / speed calculation means 23. Are separated into a component (d-axis current feedback value) in a direction matching the rotor magnetic flux and a component (q-axis current feedback value) in a direction orthogonal to the rotor magnetic flux. Subsequently, the subtractor 73 subtracts the d-axis current feedback value from the d-axis current command value as a d-axis current error, and the subtracter 74 subtracts the q-axis current feedback value from the q-axis current command value as a q-axis current error. , Respectively.

  Next, the d-axis current controller 75 inputs a d-axis current error, performs an operation such as proportional integration so that the error becomes zero, and a target voltage amount (in a direction matching the rotor magnetic flux of the AC motor 3) ( d-axis voltage command value) is calculated and output. The q-axis current controller 76 inputs a q-axis current error, performs a calculation such as proportional integration so that the error becomes zero, and obtains a target voltage amount (q-axis) in a direction orthogonal to the rotor magnetic flux of the AC motor 3. Voltage command value) is calculated and output. Subsequently, the second coordinate converter 77 is based on the d-axis voltage command value, the q-axis voltage command value, and the rotation angle from the rotation angle / speed calculation means 23, and the three-phase voltage to be applied to the terminal of the AC motor 3. Calculate and output the command amount of AC voltage.

  As described above, the calculated command amount of the three-phase AC voltage is input to the switching signal generator 25 together with the DC voltage value output from the demodulator 46. The switching signal generation unit 25 generates a pulse width modulated switching signal so that a voltage corresponding to the three-phase AC voltage command amount is applied to the terminal by matching with the DC unit voltage value. Since this switching signal is transmitted into the three-phase inverter 6 and the transistors 7a to 7f perform the switching operation, a desired voltage is applied to the AC motor 3 and the motor operation according to the command signal is performed.

  As described above, according to the in-vehicle power conversion device according to the first embodiment, when the DC voltage information of the power converter is electrically insulated and transmitted to the control unit, the power converter is provided in the power converter as in the conventional device. By mounting a high-performance microcontroller, it is not necessary to go through complicated processing procedures such as A / D conversion of DC voltage, data processing for communication, and serial data communication, and it can be realized with a simple configuration at low cost. In addition, it is easy to reduce the phase lag due to the transmission time of the DC part voltage information at the upper limit frequency of the motor control pass band, and the control responsiveness can be kept good even when the pass band upper limit frequency is high. Is possible.

  Furthermore, the communication data on the transmission path of the DC voltage information is not encoded as in the prior art, and is the same as the logical value information at other time points that remains even if the logical value information at any time point is extracted. Degree. For this reason, even if the logic of the transmission signal is temporarily mistaken due to noise superimposed on the transmission line, there is no concern that the DC voltage value will vary greatly depending on the timing of noise superimposition. It is possible to increase noise tolerance in demodulation.

In addition, in the vehicle-mounted power converter device according to the first embodiment, the mode of the motor control by the control unit 5 shown in FIG. 5 is shown, but the motor control may be realized by another configuration.
For example, the feedback information of the rotation angle and the rotation speed is calculated by the rotation angle / speed calculation means 23 based on the rotation signal output from the rotation detector 15, but the electric characteristics of the AC motor 3 without the rotation detector 15 are provided. Thus, rotation detector-less control or the like that performs estimation calculation of the rotation angle and rotation speed and uses it for the motor control calculation can be considered.

Embodiment 2. FIG.
FIG. 6 is a configuration diagram of the entire system including the in-vehicle power converter according to Embodiment 2 of the present invention. In FIG. 6, the same or corresponding parts as those in FIGS. 1 and 11 are denoted by the same reference numerals. is there. In FIG. 6, a DC-DC converter 36 is a voltage conversion circuit that converts a voltage input from the DC power supply 2 into a desired target output voltage and applies it to an electric load 35, and includes an input filter capacitor 37, a reactor, and the like. 38, transistors 39a and 39b, flywheel diodes 40a and 40b, and a smoothing capacitor 9.

  The emitter of the transistor 39a is connected to the collector of the transistor 39b, and the flywheel diode 40a has its anode connected to the emitter of the transistor 39a and its cathode connected to the collector of the transistor 39a so as to be in antiparallel with the transistor 39a. The flywheel diode 40b has an anode connected to the emitter of the transistor 39b and a cathode connected to the collector of the transistor 39b so as to be in antiparallel with the transistor 39b. The flywheel diode 40b is armed by the transistors 39a and 39b and the flywheel diodes 40a and 40b. Is configured.

One end of the reactor 38 is connected to a connection portion between the emitter of the transistor 39a and the collector of the transistor 39b, which is an intermediate point of the arm, and the other end of the reactor 38 is connected to one end of the input filter capacitor 37 and the output of the DC power source 2. Is connected to the high potential P ₀ side terminal. The other end of the input filter capacitor 37 is connected to the low potential N ₀ terminal of the output of the DC power source 2 to supply the emitter of the transistor 39 b. Further, one end of the smoothing capacitor 9 is connected to the electric load 35 as a high potential P-side output terminal of the power converter 4 together with the collector of the transistor 39a, and the other end of the smoothing capacitor 9 is connected to the DC power source 2 together with the emitter of the transistor 39b. The output is connected to the electric load 35 as a low potential N-side output terminal having the same potential as the low potential N ₀ side terminal.

The transistors 39a and 39b perform a complementary switching operation. That is, when the transistor 39a is conductive, the transistor 39b is nonconductive. Conversely, when the transistor 39a is non-conductive, the transistor 39b is conductive. If transistor 39b is conductive, the transistor 39a is non-conductive, anti-parallel flywheel diode 40a becomes reverse biased, the potential of the collector of the transistor 39b is equal to the potential of the low potential N ₀ terminal of the substantially DC power supply 2 Thus, current flows through the reactor 38 and energy is accumulated.

  When the transistor 39b is non-conductive, the transistor 39a is conductive and the flywheel diode 40b is reverse-biased, and the energy accumulated in the reactor 38 is released toward the smoothing capacitor 9 and the electric load 35. Thus, voltage conversion is performed by a series of operations for switching the transistors 39a and 39b. In order to make the output voltage of the power converter 4 follow a desired target output voltage, the control unit 5 performs an output voltage control calculation, and generates and outputs a switching signal for adjusting the duty of the transistors 39a and 39b. .

  In order to perform the output voltage control calculation, the control unit 5 receives the output side DC section voltage information of the power converter 4 together with the voltage conversion operation command signal. At this time, since the input voltage from the DC power supply 2 is further converted in the direction of further boosting, the output voltage range of the power converter 4 is about 40 [V] to several hundred [V]. On the other hand, the control unit 5 is constituted by an electronic circuit that operates in a voltage range of tens or less [V], and signal input / output between the power converter 4 and the control unit 5 is electrically insulated. Otherwise, the electronic circuit will be damaged by overvoltage.

  Therefore, as in the case of the first embodiment, the output side DC section voltage information of the power converter 4 is controlled as a modulation signal through the isolated communication element after performing delta-sigma modulation as shown in the path shown in FIG. It is transmitted to unit 5. That is, the output side DC part voltage signal of the power converter 4 detected by the voltage detector 10 is passed through the DC part voltage input interface 11 to obtain a standardized DC part voltage signal, and this standardized DC part voltage signal is converted into a delta-sigma signal. Modulated by the modulator 45 to generate a DC voltage modulated signal.

  The direct current voltage modulation signal is transmitted to the control unit 5 through the insulating communication element 13 and converted into a signal having a voltage level corresponding to the logical values “1” and “−1” at the signal input interface 20. . Further, the demodulating means 46 counts the logic state of the DC voltage modulation signal and demodulates the output DC voltage value so that it can be used for arithmetic calculation in the control calculation unit 24.

  Next, output voltage control calculation and generation of a switching signal for operating the transistor 39 will be described with reference to the drawings. FIG. 7 is a block diagram for explaining the signal flow of the output voltage control calculation in the control unit 5. In FIG. 7, first, a DC voltage modulation signal and a voltage conversion operation command signal are input from the outside of the control unit 5 and transmitted to the signal input interface 20. In response to each input signal, the signal input interface 20 performs waveform shaping to restore conversion to a desired voltage level, signal rise and fall characteristics, and the like. Thereafter, the DC voltage modulation signal is transmitted to the demodulating means 46, and the voltage conversion operation command signal is transmitted to the serial communication device 22.

  The demodulating means 46 demodulates and outputs the output side DC voltage value of the power converter 4. The serial communicator 22 receives a voltage conversion operation command signal of the DC-DC converter 36 that is input by serial communication from an external device of the in-vehicle power converter 1 (not shown), and outputs received data.

  Next, the control calculation unit 24 performs an output voltage control calculation to calculate the switching duty of the transistors 39a and 39b. Here, the control calculation unit 24 includes a voltage command generation unit 81, a subtracter 82, and a voltage controller 83, and detailed operations thereof are as follows. First, the voltage command generation means 81 receives the received data of the voltage conversion operation command signal from the serial communication device 22, decodes and outputs the output voltage command value of the power converter 4.

  Subsequently, the subtracter 82 subtracts the output side DC voltage value output from the demodulator 46 from the output voltage command value and outputs the result as an output voltage error. Next, the voltage controller 83 inputs an output voltage error, performs an operation such as proportional integration so that the error becomes zero, and calculates and outputs a target duty of switching of the transistors 39a and 39b.

  The target duty of switching output from the control calculation unit 24 is input to the switching signal generation unit 25. The switching signal generator 25 generates a switching signal based on the target duty. Since this switching signal is transmitted into the DC-DC converter 36 and the transistors 39a and 39b perform the switching operation, the output voltage of the power converter 4 can be controlled to follow and match the desired target output voltage.

  As described above, according to the in-vehicle power conversion device according to the second embodiment, the power converter output side DC section voltage information is electrically insulated and transmitted to the control unit as in the conventional device. A high-performance microcontroller can be installed inside, and there is no need to go through complicated processing procedures such as A / D conversion of DC voltage, data processing for communication, and serial data communication. is there. In addition, it is easy to reduce the phase delay due to the elapsed time of transmission of the output side DC voltage information at the passband upper limit frequency of the output voltage control, and the control response can be improved even when the passband upper limit frequency is high. It is possible to keep it good.

  Further, the communication data on the output-side DC section voltage information transmission line is not encoded as in the conventional device, and the logical value information at other time points that remains even if the logical value information at any time point is extracted. Is the same importance. For this reason, even if the logic of the transmission signal is temporarily mistaken due to noise superimposed on the transmission line, there is no concern that the DC voltage value will vary greatly depending on the timing of noise superimposition. It is possible to increase noise tolerance in demodulation.

  In the in-vehicle power conversion device according to the second embodiment, the output voltage control by the control unit 5 shown in FIG. 7 is shown. However, the output voltage control may be realized by another configuration. For example, in addition to feedback of the output side DC section voltage information of the power converter 4, the multiple feedback control system may be configured by feeding back the output current or input current of the power converter 4, The predicted value of the switching duty based on the ratio between the target output voltage value of the power converter 4 and the input side DC voltage value may be added to the output of the voltage controller 83 to compensate. Furthermore, even when the input-side DC voltage information of the power converter is transmitted after being electrically insulated from the control unit, the same configuration and operation may be performed with respect to modulation, transmission, and demodulation.

  The on-vehicle power converters according to the first embodiment and the second embodiment described above are illustrated as preferred embodiments of the present invention, and are not necessarily limited to the configuration and operation according to this embodiment. Of course, other configurations and operations may be performed without departing from the spirit of the present invention.

It is a block diagram which shows the structure of the whole system containing the vehicle-mounted power converter device which concerns on Embodiment 1 of this invention. It is a block diagram which shows the detailed structure and path | route of DC part voltage information transmission of the vehicle-mounted power converter device which concerns on Embodiment 1 of this invention. It is a wave form diagram explaining the modulation | alteration and demodulation operation | movement of the DC part voltage information of the vehicle-mounted power converter device which concerns on Embodiment 1 of this invention. It is a wave form diagram which expands time and shows the modulation | alteration and demodulation operation | movement of the DC part voltage information of the vehicle-mounted power converter device which concerns on Embodiment 1 of this invention. It is a block diagram explaining the flow of the signal of the motor control calculation of the control unit of the vehicle-mounted power converter device according to Embodiment 1 of the present invention. It is a block diagram which shows the structure of the whole system containing the vehicle-mounted power converter device which concerns on Embodiment 2 of this invention. It is a block diagram explaining the flow of the signal of the output voltage control calculation of the control unit of the vehicle-mounted power converter which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the whole system containing the vehicle-mounted power converter device which concerns on the technique 1 used as the foundation of this invention. It is a block diagram which shows the detailed structure and path | route of the vehicle-mounted power converter device which concerns on the technique 1 used as the foundation of this invention. It is a table | surface which shows the procedure list of the vehicle-mounted power converter device which concerns on the technique 1 used as the foundation of this invention. It is a block diagram which shows the structure of the whole system containing the vehicle-mounted power converter device which concerns on the technique 2 used as the foundation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle-mounted power converter 2 DC power supply 3 AC motor 4 Power converter 5 Control unit 6 Three-phase inverter 7a, 7b, 7c, 7d, 7e, 7f, 39a, 39b Transistor 8a, 8b, 8c, 8d, 8e, 8f , 40a, 40b Flywheel diode 9 Smoothing capacitor 10 Voltage detector 11 DC section voltage input interface 13 Insulated communication element 14a, 14b, 14c Motor current detector 15 Rotation detector 20 Signal input interface 21, 31 A / D converter 22 , 33 Serial communication device 23 Rotation angle / speed calculation means 24 Control calculation unit 25 Switching signal generation unit 26 Microcontroller 27, 32 Calculation processor 28, 34, 59, 66 Clock oscillator 35 Electric load 36 DC-DC converter 37 Input filter Capacitor 3 Reactor 45 Delta-sigma modulator 46 Demodulating means 51 Sampler 52, 73, 74, 82 Subtractor 53, 62 Adder 54, 56, 63, 68 Delay device 55 1-bit quantizer 57 1-bit D / A converter 58, 65 Amplifier circuit 60, 67 Frequency divider 61, 64 Sampler 69 Logic state counter 71 First coordinate converter 72 Current command generation means 75 d-axis current controller 76 q-axis current controller 77 second coordinate converter 81 Voltage command Generation means 82 Subtractor 83 Voltage controller

Claims (3)

A power converter provided between a DC power source and an electric load for performing power conversion between the DC power source and the electric load by switching of the power element, and a control unit for controlling switching of the power element. The power converter for in-vehicle use, wherein the power converter includes a voltage detector that detects a voltage of the DC unit, and a predetermined voltage change range that is detected by the voltage detector and that sets the voltage of the DC unit in advance. A DC part voltage input interface that outputs a standardized DC part voltage that is normalized with the maximum value of the delta-sigma modulator that delta-sigma-modulates the standardized DC part voltage every predetermined period to form a voltage modulation signal; and An insulation communication element that electrically insulates the voltage modulation signal and transmits the voltage modulation signal to the control unit, and the control unit inputs the transmitted voltage modulation signal. Interface, demodulating means for demodulating the voltage value of the DC section by counting the logic state of the voltage modulated signal within the predetermined period, and controlling switching of the power element based on the signal demodulated by the demodulating means A vehicle-mounted power conversion device comprising: a switching signal generation unit configured to generate a switching control signal to perform.   The electric load is a multiphase AC motor, and the power converter is an inverter that converts DC power input from the DC power source into AC power and supplies the AC power to the multiphase AC motor. Item 2. A vehicle-mounted power conversion device according to Item 1.   The in-vehicle power according to claim 1, wherein the power converter is a converter that converts an input voltage from the DC power source into a voltage that matches a desired target output voltage and supplies the converted voltage to the electric load. Conversion device.

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