Transformer control device and power conversion device

Abstract

The purpose of the present invention is to provide a transformation control device and a power conversion device that can suppress any drift of phase current in a magnetic-coupling-interleave-type chopper circuit.　In the present invention, a transformation control device for controlling a magnetic-coupling-interleave-type chopper circuit is employed as a solution, the transformation control device comprising a switching frequency setting unit for setting the switching frequency of the magnetic-coupling-interleave-type chopper circuit so as to fluctuate in time series within a prescribed frequency range, and the transformation control device generating a gate signal for transformation of the switching frequency and outputting the gate signal to the magnetic-coupling-interleave-type chopper circuit.

Description

[Technical Field]

[0001] The present invention relates to a transformer control device and a power conversion device. [Background technology]

[0002] Patent Document 1 below discloses a power conversion device that is mounted on a vehicle that runs using a motor as a power source and drives the motor by boosting a DC voltage input from a DC power supply using a multi-phase converter and outputting the boosted voltage to an inverter. The multi-phase converter includes two chopper circuits that are connected in parallel and whose reactors are magnetically coupled to each other, and uses one current sensor to accurately detect the bias of the phase currents of each chopper circuit that flow through each reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent No. 6949223 Summary of the Invention [Problem to be solved by the invention]

[0004] The multi-phase converter is a transformer circuit known as a magnetically coupled interleaved chopper circuit. In this magnetically coupled interleaved chopper circuit, if the ripple frequency of the load current of the traction motor and the repetition frequency (carrier frequency) of the gate pulses controlling the multi-phase converter are synchronized, the phase current drift may not be suppressed. This may result in a deterioration in the controllability of the magnetically coupled interleaved chopper circuit or abnormal heat generation in devices in the magnetically coupled interleaved chopper circuit.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a transformer control device and a power conversion device that are capable of suppressing the biasing of phase currents in a magnetically coupled interleaved chopper circuit. [Means for solving the problem]

[0006] A first aspect of the transformer control device of the present disclosure is a transformer control device that controls a magnetically coupled interleaved chopper circuit, and includes a switching frequency setting unit that varies the switching frequency of the magnetically coupled interleaved chopper circuit over time within a predetermined frequency range, and generates a transformer gate signal of the switching frequency and outputs it to the magnetically coupled interleaved chopper circuit.

[0007] In the transformer control device of the second aspect of the present disclosure, the switching frequency setting unit may randomly vary the switching frequency.

[0008] In the transformer control device of the third aspect of the present disclosure, the switching frequency setting unit may set the switching frequency based on a state quantity of the magnetically coupled interleaved chopper circuit.

[0009] In the transformer control device according to the fourth aspect of the present disclosure, the reactor current of each phase may be obtained by a single current sensor, and the switching frequency may be set based on the reactor current.

[0010] In the transformer control device of a fifth aspect of the present disclosure, the current sensor may detect the reactor current so that the current flow direction is the same.

[0011] In the transformer control device of a sixth aspect of the present disclosure, the switching frequency setting unit may set the switching frequency so that each phase of the magnetically coupled interleaved chopper circuit has the same frequency.

[0012] A power conversion device of a first aspect of the present disclosure includes a transformation control device according to any one of the first to sixth aspects described above, the magnetically coupled interleaved chopper circuit controlled by the transformation control device, a drive inverter provided between the magnetically coupled interleaved chopper circuit and a motor, converting DC power input from the magnetically coupled interleaved chopper circuit into AC power and outputting it to the motor, and a power generation inverter provided between the magnetically coupled interleaved chopper circuit and a generator, converting AC power input from the generator into DC power and outputting it to the magnetically coupled interleaved chopper circuit. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a transformer control device and a power conversion device that are capable of suppressing biased flow of phase current in a magnetically coupled interleaved chopper circuit. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a configuration of a power conversion device A according to an embodiment of the present disclosure. [Figure 2] 2 is a block diagram showing the configuration of a transformer control device B according to an embodiment of the present disclosure. FIG. [Figure 3] FIG. 10 is a characteristic diagram showing a change in carrier frequency in the embodiment of the present disclosure. [Figure 4] FIG. 4 is a waveform diagram illustrating a detected current according to an embodiment of the present disclosure. [Figure 5A] 1 is a first waveform diagram illustrating the operation of a buck-boost converter (magnetically coupled interleaved chopper circuit) according to an embodiment of the present disclosure. FIG. [Figure 5B] FIG. 10 is a second waveform diagram showing the operation of the buck-boost converter (magnetically coupled interleaved chopper circuit) according to the embodiment of the present disclosure. [Figure 6] 4 is a flowchart showing the operation of a voltage transformation control device B according to an embodiment of the present disclosure. BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the functional configuration of the power conversion device A in this embodiment will be described with reference to Fig. 1. As shown in the figure, this power conversion device A is provided between a battery P, a traveling motor M, and a three-phase generator G, and converts battery power (DC power) of the battery P and AC power of the traveling motor M and the three-phase generator G.

[0016] The power conversion device A is a PCU (Power Control Unit) mounted on an electric vehicle such as a hybrid vehicle or an electric car, and drives the traction motor M based on DC power from the battery P, charges the battery P with the regenerated power (AC power) from the traction motor M, and also charges the battery P with the generated power (AC power) from the phase generator G.

[0017] As shown in the figure, such a power conversion device A includes a power conversion circuit 1, a gate driver 2, and an ECU (Electronic Control Unit) 3. Also, as shown in the figure, the gate driver 2 includes a transformation gate signal generator 2a, a drive gate signal generator 2b, and a power generation gate signal generator 2c. As shown in the figure, the power conversion circuit 1 includes a step-up / step-down converter D1, a drive inverter D2, and a power generation inverter D3.

[0018] As will be described in detail later, the ECU 3 includes, as functional components, a transformation control unit that controls the step-up / step-down converter D1 via a transformation gate signal generation unit 2a, a drive control unit that controls the drive inverter D2 via a drive gate signal generation unit 2b, and a power generation control unit that controls the power generation inverter D3 via a power generation gate signal generation unit 2c.

[0019] In the power conversion device A, the voltage transformation gate signal generation unit 2a, the step-up / step-down converter D1, and the transformation control unit of the ECU 3 constitute a transformer that converts DC power and AC power between the battery P, the traction motor M, and the generator G. In addition, the voltage transformation gate signal generation unit 2a and the transformation control unit of the ECU 3 constitute a transformation control device that controls the step-up / step-down converter D1 of the power conversion circuit 1.

[0020] The power conversion device A has, as external connection terminals, a pair of battery terminals E1 and E2, three motor terminals Fu, Fv, and Fw, and three generator terminals Hu, Hv, and Hw. Of the pair of battery terminals E1 and E2, the first battery terminal E1 is connected to the positive electrode of a battery P, and the second battery terminal E2 is connected to the negative electrode of the battery P.

[0021] Of the three motor terminals Fu, Fv, and Fw, the first motor terminal Fu is connected to the U-phase terminal of the traveling motor M. The second motor terminal Fv is connected to the V-phase terminal of the traveling motor M. The third motor terminal Fw is connected to the W-phase terminal of the traveling motor M.

[0022] Of the three generator terminals Hu, Hv, and Hw, the first generator terminal Hu is connected to the U-phase terminal of the generator G. The second generator terminal Hv is connected to the V-phase terminal of the generator G. The third generator terminal Hw is connected to the W-phase terminal of the generator G.

[0023] The battery P has a positive electrode connected to the first battery terminal E1 and a negative electrode connected to the second battery terminal E2. The battery P is a secondary battery such as a lithium ion battery, and supplies (discharges) DC power to the power conversion circuit 1 of the power conversion device A and charges the DC power via the power conversion circuit 1.

[0024] The traveling motor M is a rotating electric machine connected to the power conversion device A. The traveling motor M is a three-phase electric motor with three phases, and is a load of the power conversion circuit 1. The traveling motor M has a U-phase terminal connected to the first motor terminal Fu, a V-phase terminal connected to the second motor terminal Fv, and a W-phase terminal connected to the third motor terminal Fw.

[0025] The traveling motor M has a rotating shaft (drive shaft) connected to the wheels of the electric vehicle, and applies rotational power to the wheels to rotate them. The traveling motor M generates regenerative power (AC power) when braking the electric vehicle. The regenerative power is input to the power conversion device A via the first motor terminal Fu, the second motor terminal Fv, and the third motor terminal Fw, where it is converted into DC power and charged into the battery P.

[0026] The generator G is a rotating electric machine connected to the power conversion device A. The generator G is a three-phase generator, with a U-phase terminal connected to a first generator terminal Hu, a V-phase terminal connected to a second generator terminal Hv, and a W-phase terminal connected to a third generator terminal Hw. The generator G is connected to the output shaft of a power source such as an engine mounted on an electric vehicle, and outputs generated power (AC power) to the power conversion circuit 1.

[0027] The step-up / step-down converter D1 includes a first capacitor 4, a transformer 5, four transformer IGBTs (Insulated Gate Bipolar Transistors) 6a to 6d, a second capacitor 7, and a reactor current sensor J. The driving inverter D2 includes six driving IGBTs 8a to 8f. The power generating inverter D3 includes six power generating IGBTs 9a to 9f.

[0028] The buck-boost converter D1 is a magnetically coupled interleaved chopper circuit in this disclosure. A magnetically coupled interleaved chopper circuit is also called a magnetically coupled multi-phase converter, and is configured by connecting two chopper circuits with different operating phases in parallel, with their respective reactors magnetically coupled. The buck-boost converter D1 is controlled by a transformer gate signal generator 2a to selectively perform a boost process (boost operation) or a buck process (boost operation).

[0029] The voltage step-up process (voltage step-up operation) is a process (operation) of stepping up battery power (DC power) input from a pair of battery terminals E1, E2 and outputting it to the drive inverter D2. The voltage step-down process (voltage step-down operation) is a process (operation) of stepping down DC power input from the drive inverter D2 or the power generation inverter D3 and outputting it from the pair of battery terminals E1, E2 to the battery P. In other words, the voltage step-up / step-down converter D1 is a power conversion circuit that inputs and outputs DC power bidirectionally between the battery P and the drive inverter D2 or the power generation inverter D3.

[0030] The drive inverter D2 has three switching legs, three of which are provided corresponding to the number of phases (three phases) of the traction motor M. The three switching legs are a U-phase drive switching leg, a V-phase drive switching leg, and a W-phase drive switching leg. The drive inverter D2 is a power conversion circuit that selectively performs power running operation and regenerative operation.

[0031] The power running operation is an operation in which DC power input from the buck-boost converter D1 is converted into three-phase AC power and output from the three motor terminals Fu, Fv, and Fw to the traction motor M. The regenerative operation is an operation in which regenerative power (AC power) input to the three motor terminals Fu, Fv, and Fw is converted into DC power and output to the buck-boost converter D1. The drive inverter D2 is a power circuit that converts DC power and three-phase AC power between the buck-boost converter D1 and the traction motor M.

[0032] The power generation inverter D3 is a power conversion circuit that converts the generated power (AC power) input to three generator terminals Hu, Hv, and Hw into DC power and outputs it to the step-up / step-down converter D1. The power generation inverter D3 is a power circuit that converts DC power and three-phase AC power between the step-up / step-down converter D1 and the generator G.

[0033] The configurations of the buck-boost converter D1, drive inverter D2, and power generation inverter D3 will be described in more detail below. In the buck-boost converter D1, one end of the first capacitor 4 is connected to the first battery terminal E1 and the transformer 5, and the other end is connected to the second battery terminal E2. Both ends of the first capacitor 4 are primary side terminals of the buck-boost converter D1.

[0034] That is, the first capacitor 4 is connected in parallel to the battery P and removes high-frequency noise contained in the battery power (DC power) input from the battery P to the step-up / step-down converter D1. The first capacitor 4 also smoothes ripples contained in the charging power (DC power) input from the transformer 5.

[0035] The transformer 5 includes a primary winding 5a and a secondary winding 5b. One end of the primary winding 5a and one end of the secondary winding 5b are connected to the first battery terminal E1 and one end of the first capacitor 4. The other end of the primary winding 5a is connected to the emitter terminal of the first transformer IGBT 6a and the collector terminal of the second transformer IGBT 6b. The other end of the secondary winding 5b is connected to the emitter terminal of the third transformer IGBT 6c and the collector terminal of the fourth transformer IGBT 6d.

[0036] The primary winding 5a and secondary winding 5b are electromagnetically coupled with a predetermined coupling coefficient k to form the transformer 5. That is, the primary winding 5a has a first self-inductance La according to the number of turns of the primary winding 5a. Meanwhile, the secondary winding 5b has a second self-inductance Lb according to the number of turns of the secondary winding 5b. Furthermore, the primary winding 5a and secondary winding 5b have a mutual inductance based on the above-mentioned first self-inductance La, second self-inductance Lb, and coupling coefficient k.

[0037] Of the four transformer IGBTs 6a to 6d, the first transformer IGBT 6a and the second transformer IGBT 6b are semiconductor switching elements that form an A-phase transformer switching leg in the step-up / step-down converter D1, while the third transformer IGBT 6c and the fourth transformer IGBT 6d are semiconductor switching elements that form a B-phase switching leg in the step-up / step-down converter D1.

[0038] The first transformation IGBT 6a has a collector terminal connected to the collector terminal of the third transformation IGBT 6c and one end of the second capacitor 7, and an emitter terminal connected to the other end of the primary winding 5a of the transformer 5 and the collector terminal of the second transformation IGBT 6b. The first transformation IGBT 6a also has a gate terminal connected to a first output terminal for the step-up / step-down converter D1 of the gate driver 2. The ON / OFF operation of the first transformation IGBT 6a is controlled based on a first transformation gate signal input from a transformation gate signal generation unit 2a of the gate driver 2.

[0039] The second transformer IGBT 6b has a collector terminal connected to the other end of the primary winding 5a of the transformer 5 and the emitter terminal of the first transformer IGBT 6a, and an emitter terminal connected to the emitter terminal of the fourth transformer IGBT 6d, the other end of the first capacitor 4, and the other end of the second capacitor 7. In addition, the second transformer IGBT 6b has a gate terminal connected to a second output terminal for the step-up / step-down converter D1 in the gate driver 2. The ON / OFF operation of this second transformer IGBT 6b is controlled based on a second transformation gate signal input from the transformation gate signal generation unit 2a of the gate driver 2.

[0040] The third transformation IGBT 6c has a collector terminal connected to the collector terminal of the first transformation IGBT 6a and one end of the second capacitor 7, and an emitter terminal connected to the other end of the secondary winding 5b of the transformer 5 and the collector terminal of the fourth transformation IGBT 6d. The third transformation IGBT 6c also has a gate terminal connected to a third output terminal for the step-up / step-down converter D1 in the gate driver 2. The ON / OFF operation of the third transformation IGBT 6c is controlled based on a third transformation gate signal input from the transformation gate signal generation unit 2a of the gate driver 2.

[0041] The fourth transformer IGBT 6d has a collector terminal connected to the other end of the secondary winding 5b of the transformer 5 and the emitter terminal of the third transformer IGBT 6c, and an emitter terminal connected to the emitter terminal of the second transformer IGBT 6b, the other end of the first capacitor 4, and the other end of the second capacitor 7. In addition, the fourth transformer IGBT 6d has a gate terminal connected to a fourth output terminal for the step-up / step-down converter D1 in the gate driver 2. The ON / OFF operation of the fourth transformer IGBT 6d is controlled based on a fourth transformation gate signal input from the transformation gate signal generation unit 2a of the gate driver 2.

[0042] The second capacitor 7 has one end connected to the collector terminal of the first transformer IGBT 6a and the collector terminal of the third transformer IGBT 6c, and the other end connected to the emitter terminal of the second transformer IGBT 6b, the emitter terminal of the fourth transformer IGBT 6d, the other end of the first capacitor 4, and the second battery terminal E2. Both ends of the second capacitor 7 are secondary-side input / output terminals of the buck-boost converter D1.

[0043] The second capacitor 7 smoothes ripples contained in the boosted power (DC power) input from the above-mentioned A-phase transformation switching leg and B-phase transformation switching leg, and also smoothes ripples contained in the regenerated power (DC power) input from the drive inverter D2 and the charging power (DC power) input from the power generation inverter D3.

[0044] The reactor current sensor J is a detector for detecting the state quantity of the buck-boost converter D1. The reactor current sensor J is engaged with the primary winding 5a and the secondary winding 5b of the transformer 5 so that the current flows in the same direction. The total current of the A-phase current of the buck-boost converter D1 flowing through the primary winding 5a and the B-phase current of the buck-boost converter D1 flowing through the secondary winding 5b is taken as the reactor current I L Detect as.

[0045] The A-phase current is a current that flows through the primary winding 5a based on the switching operation of the A-phase switching leg of the buck-boost converter D1, i.e., the first and second transformer IGBTs 6a and 6b, and the B-phase current is a current that flows through the secondary winding 5b based on the switching operation of the B-phase switching leg of the buck-boost converter D1, i.e., the third and fourth transformer IGBTs 6c and 6d.

[0046] The reactor current sensor J measures the reactor current I, which is the sum of the A-phase current and the B-phase current. L is output to the ECU 3 as one of the control information. Lis a power running current flowing from the primary side to the secondary side in the step-up / step-down converter D1, or a regenerative current or charging current flowing from the secondary side to the primary side.

[0047] 1, the buck-boost converter D1 is provided with a primary-side voltage sensor and a secondary-side voltage sensor in addition to the current sensor J as detectors for detecting state quantities of the buck-boost converter D1. The primary-side voltage sensor is a voltage sensor that detects a primary voltage Vp (DC voltage) on the primary side of the buck-boost converter D1, i.e., on the battery P side, and outputs the primary voltage Vp to the ECU 3.

[0048] The secondary-side voltage sensor is a voltage sensor that detects a secondary voltage Vs (DC voltage) on the secondary side of the step-up / step-down converter D1, i.e., on the drive inverter D2 side (power generation inverter D3 side), and outputs the secondary voltage Vs to the ECU 3. Note that the secondary voltage Vs is the primary voltage in the drive inverter D2 and also the secondary voltage of the power generation inverter D3.

[0049] Next, the drive inverter D2 will be described. The drive inverter D2 is an inverter circuit that is provided between the step-up / step-down converter D1, which is a transformer circuit, and the traveling motor M, and converts DC power input from the step-up / step-down converter D1 (transformer circuit) into AC power to drive the traveling motor M.

[0050] Of the six drive IGBTs 8a-8f that make up this drive inverter D2, the first drive IGBT 8a and the second drive IGBT 8b are semiconductor switching elements that make up a U-phase drive switching leg, the third drive IGBT 8c and the fourth drive IGBT 8d are semiconductor switching elements that make up a V-phase drive switching leg, and the fifth drive IGBT 8e and the sixth drive IGBT 8f are semiconductor switching elements that make up a W-phase drive switching leg.

[0051] Of the first drive IGBT 8a and the second drive IGBT 8b, the collector terminal of the first drive IGBT 8a is connected to the collector terminal of the third drive IGBT 8c and the collector terminal of the fifth drive IGBT 8e, and the emitter terminal of the first drive IGBT 8a is connected to the collector terminal of the second drive IGBT 8b and the first motor terminal Fu.

[0052] The first drive IGBT 8a has a gate terminal connected to a first output terminal for a drive inverter D2 in the gate driver 2. The ON / OFF operation of the first drive IGBT 8a is controlled based on a first drive gate signal input from a drive gate signal generation unit 2b of the gate driver 2.

[0053] The second drive IGBT 8b has a collector terminal connected to the emitter terminal of the first drive IGBT 8a and the first motor terminal Fu, and an emitter terminal connected to the emitter terminal of the fourth drive IGBT 8d and the emitter terminal of the sixth drive IGBT 8f.

[0054] The second drive IGBT 8b has a gate terminal connected to a second output terminal for the drive inverter D2 in the gate driver 2. The ON / OFF operation of the second drive IGBT 8b is controlled based on a second drive gate signal input from the drive gate signal generation unit 2b of the gate driver 2.

[0055] The third drive IGBT 8c has a collector terminal connected to the collector terminal of the first drive IGBT 8a and the collector terminal of the fifth drive IGBT 8e, and an emitter terminal connected to the collector terminal of the fourth drive IGBT 8d and the second motor terminal Fv.

[0056] Furthermore, the gate terminal of the third drive IGBT 8c is connected to the second output terminal for the drive inverter D2 in the gate driver 2. The ON / OFF operation of the third drive IGBT 8c is controlled based on a third drive gate signal input from the drive gate signal generation unit 2b of the gate driver 2.

[0057] The fourth drive IGBT 8d has a collector terminal connected to the emitter terminal of the third drive IGBT 8c and the second motor terminal Fv, and an emitter terminal connected to the emitter terminal of the second drive IGBT 8b and the emitter terminal of the sixth drive IGBT 8f.

[0058] The gate terminal of the fourth drive IGBT 8d is connected to a fourth output terminal for the drive inverter D2 in the gate driver 2. The ON / OFF operation of the fourth drive IGBT 8d is controlled based on a fourth drive gate signal input from the drive gate signal generation unit 2b of the gate driver 2.

[0059] The fifth drive IGBT 8e has a collector terminal connected to the collector terminal of the first drive IGBT 8a and the collector terminal of the third drive IGBT 8c, and an emitter terminal connected to the collector terminal of the sixth drive IGBT 8f and the third motor terminal Fw.

[0060] The gate terminal of the fifth drive IGBT 8e is connected to a fifth output terminal for the drive inverter D2 in the gate driver 2. The ON / OFF operation of the fifth drive IGBT 8e is controlled based on a fifth drive gate signal input from the drive gate signal generation unit 2b of the gate driver 2.

[0061] The sixth drive IGBT 8f has a collector terminal connected to the emitter terminal of the fifth drive IGBT 8e and the third motor terminal Fw, and an emitter terminal connected to the emitter terminal of the second drive IGBT 8b and the emitter terminal of the fourth drive IGBT 8d.

[0062] The gate terminal of the sixth drive IGBT 8f is connected to a sixth output terminal for the drive inverter D2 in the gate driver 2. The ON / OFF operation of the sixth drive IGBT 8f is controlled based on a sixth drive gate signal input from the drive gate signal generation unit 2b of the gate driver 2.

[0063] In the drive inverter D2, both ends of the mutually commonly connected U-phase driving switching leg, V-phase driving switching leg, and W-phase driving switching leg are primary-side input / output terminals of the drive inverter D2. The three midpoints of the U-phase driving switching leg, V-phase driving switching leg, and W-phase driving switching leg are respectively secondary-side input / output terminals of the drive inverter D2.

[0064] That is, the connection point between the emitter terminal of the first drive IGBT 8a and the collector terminal of the second drive IGBT 8b, the connection point between the emitter terminal of the third drive IGBT 8c and the collector terminal of the fourth drive IGBT 8d, and the connection point between the emitter terminal of the fifth drive IGBT 8e and the collector terminal of the sixth drive IGBT 8f are the above-mentioned midpoints and are secondary side input / output terminals of the drive inverter D2.

[0065] One of the primary input / output terminals of the drive inverter D2, i.e., the collector terminal of the first drive IGBT 8a, the collector terminal of the third drive IGBT 8c, and the collector terminal of the fifth drive IGBT 8e, is connected to one of the secondary input / output terminals of the step-up / step-down converter D1, i.e., one end of the second capacitor 7, the collector terminal of the first transformer IGBT 6a, and the collector terminal of the third transformer IGBT 6c.

[0066] The other of the primary input / output terminals of the drive inverter D2, i.e., the emitter terminal of the second drive IGBT 8b, the emitter terminal of the fourth drive IGBT 8d, and the emitter terminal of the sixth drive IGBT 8f, is connected to the other of the secondary input / output terminals of the step-up / step-down converter D1, i.e., the other ends of the first and second capacitors 4 and 7, the emitter terminal of the second transformer IGBT 6b, and the emitter terminal of the fourth transformer IGBT 6d.

[0067] Next, the power generation inverter D3 will be described. The power generation inverter D3 is an inverter circuit that is provided between the step-up / step-down converter D1, which is a transformer circuit, and the generator G, and converts the generated power (AC power) input from the generator G into DC power and outputs it to the step-up / step-down converter D1 (transformer circuit).

[0068] Of the six power generating IGBTs 9a-9f that make up the power generating inverter D3, the first power generating IGBT 9a and the second power generating IGBT 9b are semiconductor switching elements that make up a U-phase power generating switching leg, the third power generating IGBT 9c and the fourth power generating IGBT 9d are semiconductor switching elements that make up a V-phase power generating switching leg, and the fifth power generating IGBT 9e and the sixth power generating IGBT 9f are semiconductor switching elements that make up a W-phase power generating switching leg.

[0069] Of the first power generation IGBT 9a and the second power generation IGBT 9b, the collector terminal of the first power generation IGBT 9a is connected to the collector terminal of the third power generation IGBT 9c and the collector terminal of the fifth power generation IGBT 9e, and the emitter terminal is connected to the collector terminal of the second power generation IGBT 9b and the first generator terminal Hu.

[0070] The first power generation IGBT 9a has a gate terminal connected to a first output terminal for the power generation inverter D3 in the gate driver 2. The first power generation IGBT 9a has its ON / OFF operation controlled based on a first power generation gate signal input from a power generation gate signal generating unit 2c of the gate driver 2.

[0071] The second power generation IGBT 9b has a collector terminal connected to the emitter terminal of the first power generation IGBT 9a and the first generator terminal Hu, and an emitter terminal connected to the emitter terminal of the fourth power generation IGBT 9d and the emitter terminal of the sixth power generation IGBT 9f. The second power generation IGBT 9b has a gate terminal connected to a second output terminal for the power generation inverter D3 in the gate driver 2. The second power generation IGBT 9b has its ON / OFF operation controlled based on a second power generation gate signal input from a power generation gate signal generation unit 2c of the gate driver 2.

[0072] The third power generation IGBT 9c has a collector terminal connected to the collector terminal of the first power generation IGBT 9a and the collector terminal of the fifth power generation IGBT 9e, and an emitter terminal connected to the collector terminal of the fourth power generation IGBT 9d and the second generator terminal Hv. The third power generation IGBT 9c has a gate terminal connected to a third output terminal for the power generation inverter D3 in the gate driver 2. The ON / OFF operation of the third power generation IGBT 9c is controlled based on a third power generation gate signal input from a power generation gate signal generation unit 2c of the gate driver 2.

[0073] The fourth power generating IGBT 9d has a collector terminal connected to the emitter terminal of the third power generating IGBT 9c and the second generator terminal Hv, and an emitter terminal connected to the emitter terminal of the second power generating IGBT 9b and the emitter terminal of the sixth power generating IGBT 9f. The fourth power generating IGBT 9d has a gate terminal connected to a fourth output terminal for the power generating inverter D3 in the gate driver 2. The ON / OFF operation of the fourth power generating IGBT 9d is controlled based on a fourth power generating gate signal input from the power generating gate signal generating unit 2c of the gate driver 2.

[0074] The fifth power generation IGBT 9e has a collector terminal connected to the collector terminal of the first power generation IGBT 9a and the collector terminal of the third power generation IGBT 9c, and an emitter terminal connected to the collector terminal of the sixth power generation IGBT 9f and the third generator terminal Hw. The fifth power generation IGBT 9e has a gate terminal connected to a fifth output terminal for the power generation inverter D3 in the gate driver 2. The ON / OFF operation of the fifth power generation IGBT 9e is controlled based on a fifth power generation gate signal input from the power generation gate signal generation unit 2c of the gate driver 2.

[0075] The sixth power generating IGBT 9f has a collector terminal connected to the emitter terminal of the fifth power generating IGBT 9e and the third generator terminal Hw, and an emitter terminal connected to the emitter terminal of the second power generating IGBT 9b and the emitter terminal of the fourth power generating IGBT 9d. The sixth power generating IGBT 9f has a gate terminal connected to a sixth output terminal for the power generating inverter D3 in the gate driver 2. The sixth power generating IGBT 9f has its ON / OFF operation controlled based on a sixth power generating gate signal input from the power generating gate signal generating unit 2c of the gate driver 2.

[0076] In the power generation inverter D3, the three midpoints of the U-phase power generation switching leg, the V-phase power generation switching leg, and the W-phase power generation switching leg are primary-side input / output terminals of the power generation inverter D3. That is, the connection point between the emitter terminal of the first power generation IGBT 9a and the collector terminal of the second power generation IGBT 9b, the connection point between the emitter terminal of the third power generation IGBT 9c and the collector terminal of the fourth power generation IGBT 9d, and the connection point between the emitter terminal of the fifth power generation IGBT 9e and the collector terminal of the sixth power generation IGBT 9f are the midpoints and primary-side input / output terminals of the power generation inverter D3.

[0077] Of the three primary side input / output terminals of the power generation inverter D3, the midpoint (first primary side input / output terminal) of the U-phase power generation switching leg is connected to the first generator terminal Hu of the power conversion device A. The midpoint (second primary side input / output terminal) of the V-phase power generation switching leg is connected to the second generator terminal Hv of the power conversion device A. The midpoint (third primary side input / output terminal) of the W-phase power generation switching leg is connected to the third generator terminal Hv of the power conversion device A.

[0078] The ends of the U-phase power generation switching leg, the V-phase power generation switching leg, and the W-phase power generation switching leg, which are connected in parallel to one another in the power generation inverter D3, are secondary-side input / output terminals of the power generation inverter D3. That is, the collector terminal of the first power generation IGBT 9a, the collector terminal of the third power generation IGBT 9c, the collector terminal of the fifth power generation IGBT 9e, the emitter terminal of the second power generation IGBT 9b, the emitter terminal of the fourth power generation IGBT 9d, and the emitter terminal of the sixth power generation IGBT 9f are the secondary-side input / output terminals.

[0079] As shown in the figure, the secondary-side input / output terminals of the power generating inverter D3 are connected to the secondary-side input / output terminals of the step-up / step-down converter D1 and the primary-side input / output terminals of the drive inverter D2. That is, the power generating inverter D3 inputs and outputs DC power to and from the step-up / step-down converter D1.

[0080] Furthermore, the transformer IGBTs 6a-6d of the step-up / step-down converter D1, the drive IGBTs 8a-8f of the drive inverter D2, and the power generating IGBTs 9a-9f of the power generating inverter D3 each have a free wheel diode. The cathode terminal of each IGBT is connected to the collector terminal, and the anode terminal is connected to the emitter terminal. The free wheel diode is used to pass a free wheel current from the anode terminal to the cathode terminal when the IGBT is in the OFF state.

[0081] Next, a description will be given of the gate driver 2. The gate driver 2 drives the step-up / step-down converter D1, the drive inverter D2, and the power generation inverter D3 based on a plurality of duty command values ​​(a duty manipulated variable for voltage transformation, a duty manipulated variable for drive, and a duty manipulated variable for power generation) input from the ECU 3.

[0082] That is, the voltage transformation gate signal generating unit 2a is a drive circuit for the voltage step-up / step-down converter D1, and is a drive signal generating circuit that generates first to fourth voltage transformation gate signals based on various voltage transformation operation amounts input from the ECU 3. For example, the voltage transformation gate signal generating unit 2a compares the voltage transformation duty operation amount with a carrier wave (triangular wave) having a cycle corresponding to the voltage transformation carrier frequency, thereby generating PWM (Pulse Width Modulation) signals having a repetition frequency and duty ratio according to the voltage transformation carrier frequency and the voltage transformation duty operation amount as the first to fourth voltage transformation gate signals.

[0083] The transformer gate signal generator 2a outputs a first transformer gate signal from a first output terminal for the buck-boost converter D1 to the gate terminal of the first transformer IGBT 6a. The transformer gate signal generator 2a outputs a second transformer gate signal from a second output terminal for the buck-boost converter D1 to the gate terminal of the second transformer IGBT 6b. The transformer gate signal generator 2a outputs a third transformer gate signal from a third output terminal for the buck-boost converter D1 to the gate terminal of the third transformer IGBT 6c. The transformer gate signal generator 2a outputs a fourth transformer gate signal from a fourth output terminal for the buck-boost converter D1 to the gate terminal of the fourth transformer IGBT 6d.

[0084] Here, of the first to fourth transformer gate signals, the first and second transformer gate signals are gate pulse signals (PWM signals) that drive the A-phase transformer switching legs (first transformer IGBT 6a and second transformer IGBT 6b) of the buck-boost converter D1, and the third and fourth transformer gate signals are gate pulse signals (PWM signals) that drive the B-phase transformer switching legs (third transformer IGBT 6c and fourth transformer IGBT 6d) of the buck-boost converter D1.

[0085] The first and second transformer gate signals and the third and fourth transformer gate signals have a phase difference around switching, for example, of 180°. In other words, the A-phase transformer switching leg (first transformer IGBT 6a and second transformer IGBT 6b) driven by the first and second transformer gate signals and the B-phase transformer switching leg (third transformer IGBT 6c and fourth transformer IGBT 6d) driven by the third and fourth transformer gate signals perform switching operations with a phase difference of, for example, 180°.

[0086] The drive gate signal generation unit 2b is a drive circuit for the drive inverter D2, and is a drive signal generation circuit that generates first to sixth drive gate signals based on the drive duty manipulated variable input from the ECU 3. For example, the drive gate signal generation unit 2b compares the drive duty manipulated variable with a carrier wave (triangular wave) having a period corresponding to the drive carrier frequency, thereby generating PWM signals having a repetition frequency (repetition period) and duty ratio according to the drive carrier frequency and the drive duty manipulated variable as the first to sixth drive gate signals.

[0087] The drive gate signal generation unit 2b outputs a first drive gate signal from a first output terminal for the drive inverter D2 to the gate terminal of the first drive IGBT 8a. The drive gate signal generation unit 2b outputs a second drive gate signal from a second output terminal for the drive inverter D2 to the gate terminal of the second drive IGBT 8b. The drive gate signal generation unit 2b outputs a third drive gate signal from a third output terminal for the drive inverter D2 to the gate terminal of the third drive IGBT 8c.

[0088] The drive gate signal generation unit 2b outputs a fourth drive gate signal from the fourth output terminal for the drive inverter D2 to the gate terminal of the fourth drive IGBT 8d. The drive gate signal generation unit 2b outputs a fifth drive gate signal from the fifth output terminal for the drive inverter D2 to the gate terminal of the fifth drive IGBT 8e. The drive gate signal generation unit 2b outputs a sixth drive gate signal from the sixth output terminal for the drive inverter D2 to the gate terminal of the sixth drive IGBT 8f.

[0089] The power generation gate signal generator 2c is a drive circuit for the power generation inverter D3, and is a drive signal generator circuit that generates first to sixth power generation gate signals based on the power generation duty manipulated variable input from the ECU 3. For example, the power generation gate signal generator 2c compares the power generation duty manipulated variable with a carrier wave (triangular wave) having a cycle corresponding to the power generation carrier frequency, thereby generating PWM signals having a repetition frequency and duty ratio according to the power generation carrier frequency and the power generation duty command value as the first to sixth power generation gate signals.

[0090] The power generation gate signal generation unit 2c outputs a first power generation gate signal from a first output terminal for the power generation inverter D3 to the gate terminal of the first power generation IGBT 9a. The power generation gate signal generation unit 2c outputs a second power generation gate signal from a second output terminal for the power generation inverter D3 to the gate terminal of the second power generation IGBT 9b. The power generation gate signal generation unit 2c outputs a third power generation gate signal from a third output terminal for the power generation inverter D3 to the gate terminal of the third power generation IGBT 9c.

[0091] The power generation gate signal generation unit 2c outputs a fourth power generation gate signal from the fourth output terminal for the power generation inverter D3 to the gate terminal of the fourth power generation IGBT 9d. The power generation gate signal generation unit 2c outputs a fifth power generation gate signal from the fifth output terminal for the power generation inverter D3 to the gate terminal of the fifth power generation IGBT 9e. The power generation gate signal generation unit 2c outputs a sixth power generation gate signal from the sixth output terminal for the power generation inverter D3 to the gate terminal of the sixth power generation IGBT 9f.

[0092] The first to fourth transformer gate signals generated by the transformer gate signal generating unit 2a are drive signals provided with a well-known dead time to avoid through current in the A-phase transformer switching leg and B-phase switching leg of the step-up / step-down converter D1.

[0093] The first to sixth driving gate signals generated by the driving gate signal generating unit 2b are driving signals provided with a well-known dead time to avoid through current in the U-phase driving switching leg, the V-phase driving switching leg, and the W-phase driving switching leg.

[0094] The first to sixth power generation gate signals generated by the power generation gate signal generating unit 2c are drive signals provided with a well-known dead time to avoid through current in the U-phase power generation switching leg, the V-phase power generation switching leg, and the W-phase power generation switching leg.

[0095] The ECU3 is a control device that feedback controls the step-up / step-down converter D1, the drive inverter D2, and the power generation inverter D3 based on the detection values ​​(voltage detection values) of the various voltage sensors mentioned above, the detection values ​​(current detection values) of the various current sensors, control commands input from a higher-level control device (vehicle control device), and a pre-stored control program.

[0096] That is, the ECU 3 is a software control device that feedback controls the step-up / step-down converter D1, the drive inverter D2, and the power generation inverter D3 in cooperation with a control program (software resource) and hardware resources such as an arithmetic circuit, a memory circuit, and various input / output circuits.

[0097] The ECU 3 has a plurality of functional components configured by the cooperation of software resources and hardware resources, namely, a transformation control unit for the buck-boost converter D1 that generates a transformation duty command value, a drive control unit for the drive inverter D2 that generates a drive duty command value, and a power generation control unit for the power generation inverter D3 that generates a power generation duty command value.

[0098] The ECU 3 generates first to fourth transformation gate signals by outputting the transformation duty command value generated by the transformation control unit to the transformation gate signal generation unit 2a of the gate driver 2. The ECU 3 generates first to sixth driving gate signals by outputting the driving duty command value generated by the driving control unit to the driving gate signal generation unit 2b of the gate driver 2. The ECU 3 generates first to sixth driving gate signals by outputting the power generation duty command value generated by the power generation control unit to the power generation gate signal generation unit 2c of the gate driver 2.

[0099] Next, a detailed configuration (control configuration) of the transformation control unit B in the ECU 3 will be described with reference to Fig. 2. The transformation control unit B is a characteristic functional component of the power conversion device A according to this embodiment, and constitutes a transformation control device together with the transformation gate signal generation unit 2a.

[0100] That is, the transformation control device according to this embodiment is configured by a transformation control unit B and a transformation gate signal generation unit 2a, and controls a step-up / step-down converter D1 (magnetically coupled interleaved chopper circuit), which is a transformation circuit. Note that in the ECU 3, the drive control unit and power generation control unit other than the transformation control unit B are similar to well-known ones, and therefore a detailed description of their configuration (control configuration) will be omitted.

[0101] 2, the transformer control unit B includes, as components, a target value setting unit 10, a voltage control unit 11, a current control unit 12, a duty control unit 13, a carrier frequency setting unit 14, a random number generation unit 15, and an adder 16. Of these components, the carrier frequency setting unit 14, the random number generation unit 15, and the adder 16 constitute the switching frequency setting unit of the present invention.

[0102] The target value setting unit 10 is a functional component that generates a secondary-side voltage command value X1 based on an externally input control command X0. This secondary-side voltage command value X1 is a target value (transformation target value) of the secondary voltage Vs of the buck-boost converter D1. In other words, the secondary-side voltage command value X1 is a value that specifies the transformation ratio of the buck-boost converter D1, i.e., the magnitude of the secondary voltage Vs relative to the primary voltage Vp.

[0103] The target value setting unit 10 outputs such secondary-side voltage command value X1 to the voltage control unit 11. The control command X0 is a control command input from a higher-level control device (vehicle control device). The primary voltage Vp is a detection value of a primary-side voltage sensor provided on the primary side (battery P side) of the step-up / step-down converter D1. The secondary voltage Vs is a detection value of a secondary-side voltage sensor provided on the secondary side (driving inverter D2 side) of the step-up / step-down converter D1.

[0104] The voltage control unit 11 is a functional component that calculates a reactor current command value X2 based on the secondary-side voltage command value X1 and the secondary voltage Vs. The voltage control unit 11 is a well-known PID controller. More specifically, the voltage control unit 11 includes a proportional voltage control unit that generates a proportional reactor current command value and an integral voltage control unit that generates an integral reactor current command value.

[0105] The proportional voltage control unit generates a proportional reactor current command value by multiplying the difference between the voltage command value X1 and the secondary voltage Vs by a proportional voltage gain. The integral voltage control unit generates an integral reactor current command value by multiplying the difference between the voltage command value X1 and the secondary voltage Vs by an integral voltage gain and performing integration processing. The reactor current command value X2 is the sum of the proportional reactor current command value and the integral reactor current command value. The voltage control unit 11 outputs the reactor current command value X2 to the current control unit 12.

[0106] The current control unit 12 calculates the reactor current command value X2 and the reactor current I LThe current control unit 12 is a functional component that calculates a reactor voltage command value X3 based on the proportional current control unit 12. The current control unit 12 is a well-known PID controller, similar to the voltage control unit 11. That is, the current control unit 12 includes a proportional current control unit that generates a proportional reactor voltage command value and an integral current control unit that generates an integral reactor voltage command value.

[0107] The proportional current control section calculates the current command value X2 and the reactor current I L The proportional reactor voltage command value is generated by multiplying the difference between the current command value X2 and the reactor current I by the proportional current gain. L The difference between these values ​​is multiplied by an integral current gain and integrated to generate an integral reactor voltage command value. The reactor voltage command value X3 is the sum of the proportional reactor voltage command value and the integral reactor voltage command value. The current control unit 12 outputs the reactor voltage command value X3 to the duty control unit 13.

[0108] The duty control unit 13 is a functional component that calculates an A-phase duty command value X4 for the A-phase transformer switching leg and a B-phase duty command value X5 for the B-phase transformer switching leg based on the reactor voltage command value X3. The duty control unit 13 outputs the A-phase duty command value X4 and the B-phase duty command value X5 to the transformation gate signal generation unit 2a of the gate driver 2.

[0109] As described above, the buck-boost converter D1 includes a phase A transformer switching leg and a phase B switching leg, which are controlled by first and second transformer gate signals and third and fourth transformer gate signals that are 180° out of phase with each other.

[0110] In order to accommodate such a two-phase configuration of the buck-boost converter D1, the duty control unit 13 generates an A-phase duty command value X4 and a B-phase duty command value X5. That is, the A-phase duty command value X4 is a manipulated variable that specifies the duty ratios of the first and second transformation gate signals that control the A-phase transformation switching leg. Also, the B-phase duty command value X5 is a manipulated variable that specifies the duty ratios of the third and fourth transformation gate signals that control the B-phase transformation switching leg.

[0111] The carrier frequency setting unit 14 sets the primary voltage Vp, the secondary voltage Vs, and the reactor current I L It is a functional component that sets the carrier frequency fc (kHz) based on the above. The carrier frequency fc is the repetition frequency of the first to fourth transformer gate signals, that is, the repetition frequency of the switching operations in the A-phase transformer switching leg and the B-phase transformer switching leg. The carrier frequency fc is, for example, any frequency in the frequency range of 6 to 12 kHz.

[0112] The carrier frequency setting unit 14 calculates the primary voltage Vp, the secondary voltage Vs, and the reactor current I by using a carrier map (three-dimensional map) stored in advance inside. L The carrier frequency setting unit 14 sets the carrier frequency fc by searching based on the following: The carrier frequency setting unit 14 outputs a frequency designation signal X6 indicating the carrier frequency fc to the adder 16.

[0113] The random number generation unit 15 is a random number generator that generates an arbitrary integer as a random number X7. The random number generation unit 15 generates the random number X7 under a preset generation range and generation conditions. The generation range is from -200 to +200. The generation conditions are as follows: n and the random number y generated at the next time (n+1) n+1 This is the difference between.

[0114] That is, the random number generator 15 generates the random number y n+1 and a random number y n A random number y is calculated so that the difference between the two exceeds a preset threshold Y. n+1Generate a random number y at time (n+1). n+1 is the random number y at time n n Based on the above generation range and generation conditions, the random number generation unit 15 generates a random number X7 that dynamically changes within the integer range of -200 to +200. The random number generation unit 15 outputs the random number X7 to the adder 16.

[0115] The adder 16 adds a random number X7 to the frequency specification signal X6 and outputs the result as a carrier frequency manipulation signal X8 to the transformation gate signal generation unit 2a of the gate driver 2. Since the carrier frequency manipulation signal X8 is obtained by adding the random number X7 to the frequency specification signal X6, it is a time-series signal that changes in a time-series manner within the range of -200 Hz to +200 Hz centered on the carrier frequency fc (kHz).

[0116] Such carrier frequency manipulation signal X8 defines the repetition frequency of the first to fourth transformation gate signals (PWM signals) in the transformation gate signal generation unit 2a that generates the first to fourth transformation gate signals. Since the first to fourth transformation gate signals control the switching operation of the buck-boost converter D1, the carrier frequency manipulation signal X8 ultimately controls the switching frequency and switching timing in the switching operation of the buck-boost converter D1.

[0117] Next, the operation of the main parts of the power conversion device A according to this embodiment, that is, the control operation of the transformation control unit B, will be described with reference to the flowchart of FIG.

[0118] In the transformer control unit B, first, the carrier frequency setting unit 14 acquires the primary voltage Vp, the secondary voltage Vs, and the reactor current IL to generate a frequency assignment signal X6 (step S1). The carrier frequency setting unit 14 sets the carrier frequency fc by searching a carrier map using the primary voltage Vp, the secondary voltage Vs, and the reactor current IL, and outputs the frequency assignment signal X6 indicating the carrier frequency fc to the adder 16.

[0119] Then, carrier frequency fc (kHz) is randomized within the range of −200 Hz to +200 Hz by adding frequency designation signal X6 to random number X7 in adder 16 (step S2). That is, adder 16 adds random number X7 in the range of −200 to +200 generated by random number generator 15 to carrier frequency fc (kHz), thereby generating carrier frequency manipulation signal X8 that changes in a time series manner within the range of −200 Hz to +200 Hz centered on carrier frequency fc (kHz).

[0120] Meanwhile, in the transformer control unit B, the target value setting unit 10 receives the control command X0 and sets a secondary side voltage command value X1 (step S3). This secondary side voltage command value X1 is output from the target value setting unit 10 to the voltage control unit 11.

[0121] In the transformer control unit B, the voltage control unit 11 takes in the secondary side voltage command value X1 and the secondary voltage Vs to set a reactor current command value X2 (step S4). The reactor current command value X2 is then output from the voltage control unit 11 to the current control unit 12.

[0122] In the transformer control unit B, the current control unit 12 calculates the reactor current command value X2 and the reactor current I L The duty command value X3 is set by taking in the above (step S5). Then, the duty command value X3 is output from the current control unit 12 to the duty control unit 13.

[0123] In the transformation control unit B, the duty control unit 13 takes in the duty command value X3 to generate an A-phase duty control input X4 and a B-phase duty control input X5 (step S6). The B-phase duty control input X5 and the B-phase duty control input X5 are then output from the duty control unit 13 to the transformation gate signal generation unit 2a of the gate driver 2.

[0124] Then, the transformer gate signal generator 2a generates first to fourth transformer gate signals (step S7) by receiving the A-phase duty cycle manipulated variable X4, the B-phase duty cycle manipulated variable X5, and the frequency designation signal X8 from the transformer control unit B. Then, the first to fourth transformer gate signals are output from the transformer gate signal generator 2a to the buck-boost converter D1, causing the buck-boost converter D1 to perform a desired buck-boost operation.

[0125] Here, the frequency specification signal X8 is a manipulation variable that randomly sets the repetition frequency (repetition period) of the first to fourth transformation gate signals in a time series. The first to fourth transformation gate signals generated based on the frequency specification signal X8 vary in a time series within a range of ±200 Hz around the center frequency.

[0126] That is, when the Chariah frequency fc set by the carrier frequency setting unit 14 is 6 kHz, for example, the carrier frequency in the A phase of the buck-boost converter D1 (A phase carrier frequency) and the carrier frequency in the B phase of the buck-boost converter D1 (B phase carrier frequency) fluctuate randomly between 5.8 kHz and 6.2 kHz as shown in FIG. 4.

[0127] Furthermore, the A-phase carrier frequency and the B-phase carrier frequency change in synchronization with each other and are set to the same value. That is, as shown by the dashed dotted line in Figure 4, the A-phase carrier frequency and the B-phase carrier frequency change at the same timing, and at a certain time, the A-phase carrier frequency and the B-phase carrier frequency are the same frequency.

[0128] Of these first to fourth transformer gate signals, the first and second transformer gate signals and the third and fourth transformer gate signals have a phase difference of 180°, so in the buck-boost converter D1, the A-phase transformer switching leg and the B-phase switching leg perform switching operations with a phase difference of 180°. As a result, the A-phase current and the B-phase current become currents with ripples that are out of phase with each other, as shown in Figures 5A and 5B, for example.

[0129] 5A and 5B, P1 indicates a peak point due to the ripple of the A-phase current, and P2 indicates a peak point due to the ripple of the B-phase current. L is the total current of the A-phase current and the B-phase current, and therefore has a ripple waveform in which the ripple of the A-phase current and the ripple of the B-phase current are combined, as shown in the figure.

[0130] Such peak points P1 and P2 occur alternately on the time axis as shown in the figure, due to the relationship in which the A-phase transformer switching leg and the B-phase switching leg perform switching operations with a phase difference of 180°.

[0131] Such a reactor current I L In this case, a deviation (drift) occurs between the A-phase current and the B-phase current, and the L of the reactor changes with the current (current superposition characteristic), causing peak points P1 and P2 to be at different levels, as shown in Fig. 5A. On the other hand, if no deviation (drift) occurs between the A-phase current and the B-phase current, peak points P1 and P2 will be at the same level, as shown in Fig. 5B.

[0132] A current imbalance between the A-phase current and the B-phase current can occur when the ripple frequency of the load current of the traction motor M and the repetition frequency of the first to fourth transformer gate signals (gate pulses) that control the buck-boost converter D1 (magnetically coupled interleaved chopper circuit), i.e., the carrier frequency fc, are synchronized. Such a current imbalance can deteriorate the controllability of the buck-boost converter D1 and cause abnormal heat generation in devices such as the transformer IGBTs 6a to 6d in the buck-boost converter D1.

[0133] To cope with this imbalance between the A-phase current and the B-phase current, the transformer control unit B uses an adder 16 to randomize the carrier frequency fc (frequency designation signal X6) set by the carrier frequency setting unit 14 using a random number X7 generated by a random number generation unit 15. Then, the transformer control unit B outputs a carrier frequency manipulation signal X8 to the transformer gate signal generation unit 2a, which randomly varies the carrier frequency fc (kHz) within a range of −200 Hz to +200 Hz.

[0134] As a result, the transformation gate signal generating unit 2a generates first to fourth transformation gate signals whose repetition frequencies change randomly within the range of −200 Hz to +200 Hz centered on the carrier frequency fc (kHz) in accordance with the carrier frequency operation signal X8, and drives the step-up / step-down converter D1.

[0135] The transformer control device according to this embodiment can prevent the ripple frequency of the load current of the traction motor M from being synchronized with the repetition frequency of the first to fourth transformer gate signals that control the buck-boost converter D1. Therefore, this embodiment can provide a transformer control device and a power conversion device that can suppress biasing of the A-phase current and B-phase current in the buck-boost converter D1.

[0136] Figure 6 shows the relationship between the first to fourth transformer gate signals and the primary voltage Vp and secondary voltage Vs. When the repetition period is Ta, focusing on phase A, the primary voltage Vp increases and the secondary voltage Vs decreases when the second transformer gate signal turns "ON." As a result, the phase A current increases.

[0137] Similarly, when the repetition period is Ta, focusing on the B phase, the primary voltage Vp decreases and the secondary voltage Vs increases when the fourth transformer gate signal turns "ON." As a result, the B phase current decreases. Therefore, when the repetition period is Ta, the A phase current tends to be larger than the B phase current.

[0138] In contrast, when the repetition period is Tb, the magnitude relationship between the primary voltage Vp and the secondary voltage Vs at the ON timing of the second and fourth transformer gate signals, which occurs when the repetition period is Ta, is alleviated. As a result, the uneven flow of the A-phase current and the B-phase current is suppressed. In other words, by simultaneously changing the ON timing of the A-phase second transformer gate signal and the B-phase fourth transformer gate signal to the same frequency, it is possible to suppress the uneven flow of the A-phase current and the B-phase current.

[0139] The present invention is not limited to the above-described embodiment, and the following modifications are possible. (1) In the above embodiment, the step-up / step-down converter D1, i.e., the magnetically coupled interleaved chopper circuit having a two-phase configuration of phases A and B, has been described, but the present invention is not limited to this. In other words, the present invention can also be applied to a magnetically coupled interleaved chopper circuit having a three-phase or more configuration.

[0140] (2) In the above embodiment, biasing of the A-phase current and the B-phase current is suppressed by driving the buck-boost converter D1 using the first to fourth transformer gate signals whose repetition frequency varies randomly within a range of -200 Hz to +200 Hz centered on the carrier frequency fc (kHz), but the present invention is not limited to this. The variation in the repetition frequency (repetition period) of the first to fourth transformer gate signals does not necessarily have to be random, and may vary with some regularity.

[0141] (3) In the above embodiment, the fluctuation range of the carrier frequency fc is set to ±200 Hz, but the present invention is not limited to this. That is, the fluctuation range of the carrier frequency fc is set appropriately in consideration of the overall controllability of the buck-boost converter D1.

[0142] (4) Although not provided in the above embodiment, the reactor current I L A duty correction unit may be provided that detects the bias of the A-phase current and the B-phase current based on the above and adjusts the duty ratio of the first and second transformer gate signals for the A-phase or the third and fourth transformer gate signals for the B-phase according to the magnitude of the bias.

[0143] This duty correction unit adjusts the duty ratio in the switching operation of phase A or phase B, making it possible to equalize the time intervals between peak points P1 and P2 that alternate on the time axis, thereby improving the accuracy of detecting drift current.

[0144] (5) In the above embodiment, the carrier frequency setting unit 14 calculates the primary voltage Vp, the secondary voltage Vs, and the reactor current I, which are state quantities of the step-up / step-down converter D1 (magnetically coupled interleaved chopper circuit). L However, the present invention is not limited to this. For example, the carrier frequency fc may be set based on a transformation ratio calculated from the primary voltage Vp and the secondary voltage Vs, and the switching frequency may be set by randomizing the carrier frequency fc.

[0145] (5) In the above embodiment, a single reactor current sensor J is used to measure the total current of the A-phase current and the B-phase current as the reactor current I L However, the present invention is not limited to this. Two current sensors may be provided to detect the A-phase current and the B-phase current separately.

[0146] (6) In the above embodiment, the power conversion circuit 1 uses IGBTs as the semiconductor switching elements, but the present invention is not limited to this. For example, MOSFETs may be used as the semiconductor switching elements. [Industrial Applicability]

[0147] The present disclosure can be used in a transformer control device and a power conversion device. [Explanation of symbols]

[0148] A Power conversion device B Transformer control section D1 Buck-boost converter (magnetically coupled interleaved chopper circuit) D2 Drive inverter D3 Power generation inverter E1, E2 Battery terminal Fu, Fv, Fw motor terminals G Generator (rotating electric machine) Hu, Hv, Hw generator terminals J Reactor Current Sensor P battery M Travel motor (rotating electric machine) 1 Power conversion circuit 2 Gate Drivers 2a Transformer gate signal generator 2b Drive gate signal generator 2c Power generation gate signal generator 3 ECU(Electronic Control Unit) 4. First Capacitor 5. Transformer 5a primary winding 5b Secondary winding 6a~6d Transformer IGBTs 7 Second Capacitor 8a~8f drive IGBT 9a~9f Power generation IGBT 10 Target value setting section 11 Voltage control section 12 Current control section 13 Duty control section 14 Carrier frequency setting section 15 Random number generator 16 Adder

Claims

1. A transformer control device for controlling a magnetically coupled interleaved chopper circuit, comprising: a switching frequency setting unit that time-series varies a switching frequency of the magnetically coupled interleaved chopper circuit within a predetermined frequency range; a transformer gate signal of the switching frequency is generated and output to the magnetically coupled interleaved chopper circuit; A transformer control device characterized in that a reactor current of each phase is acquired by a single current sensor, and the switching frequency is set based on the reactor current.

2. The transformer control device according to claim 1 , wherein the switching frequency setting unit randomly varies the switching frequency.

3. The transformer control device according to claim 1 , wherein the switching frequency setting unit sets the switching frequency based on a state quantity of the magnetically coupled interleaved chopper circuit.

4. A transformer control device as described in Claim 1, wherein the current sensor detects the reactor current so that the current flow direction is the same.

5. A transformer control device described in any one of claims 1 to 4, wherein the switching frequency setting unit sets the switching frequency so that each phase of the magnetically coupled interleaved chopper circuit has the same frequency.

6. A voltage transformer control device according to any one of claims 1 to 5, the magnetically coupled interleaved chopper circuit controlled by the transformer control device; a drive inverter provided between the magnetically coupled interleaved chopper circuit and a motor, which converts DC power input from the magnetically coupled interleaved chopper circuit into AC power and outputs the AC power to the motor; a power generation inverter provided between the magnetically coupled interleaved chopper circuit and a generator, which converts AC power input from the generator into DC power and outputs the DC power to the magnetically coupled interleaved chopper circuit; A power conversion device comprising:

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